通常，在編碼時，我們必須處理其中包含數(shù)十個字段的一些POJO對象。 很多時候，我們通過一個帶有數(shù)十個參數(shù)的構(gòu)造函數(shù)來初始化這些類，這以任何可能的想象的方式都是可怕的。 除此之外，使用這些構(gòu)造函數(shù)的函數(shù)幾乎不可測試。 讓我們仔細(xì)研究一下使用Builder來改變這種情況，以及Hamcrest匹配器和Guava Predicates對它進行單元測試。 讓我們開始看一下POJO類。

SomeBigPojo.java

package pl.grzejszczak.marcin.junit.matchers.pojo;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 21:05*/ public class SomeBigPojo {private String stringField0;private Integer integerField0;private Boolean booleanField0;private String stringField1;private Integer integerField1;private Boolean booleanField1;private String stringField2;private Integer integerField2;private Boolean booleanField2;private String stringField3;private Integer integerField3;private Boolean booleanField3;private String stringField4;private Integer integerField4;private Boolean booleanField4;private String stringField5;private Integer integerField5;private Boolean booleanField5;private String stringField6;private Integer integerField6;private Boolean booleanField6;private String stringField7;private String stringField8;private String stringField9;public SomeBigPojo(String stringField0, Integer integerField0, Boolean booleanField0, String stringField1, Integer integerField1, Boolean booleanField1, String stringField2, Integer integerField2, Boolean booleanField2, String stringField3, Integer integerField3, Boolean booleanField3, String stringField4, Integer integerField4, Boolean booleanField4, String stringField5, Integer integerField5, Boolean booleanField5, String stringField6, Integer integerField6, Boolean booleanField6, String stringField7, String stringField8, String stringField9) {this.stringField0 = stringField0;this.integerField0 = integerField0;this.booleanField0 = booleanField0;this.stringField1 = stringField1;this.integerField1 = integerField1;this.booleanField1 = booleanField1;this.stringField2 = stringField2;this.integerField2 = integerField2;this.booleanField2 = booleanField2;this.stringField3 = stringField3;this.integerField3 = integerField3;this.booleanField3 = booleanField3;this.stringField4 = stringField4;this.integerField4 = integerField4;this.booleanField4 = booleanField4;this.stringField5 = stringField5;this.integerField5 = integerField5;this.booleanField5 = booleanField5;this.stringField6 = stringField6;this.integerField6 = integerField6;this.booleanField6 = booleanField6;this.stringField7 = stringField7;this.stringField8 = stringField8;this.stringField9 = stringField9;}public String getStringField0() {return stringField0;}public void setStringField0(String stringField0) {this.stringField0 = stringField0;}public Integer getIntegerField0() {return integerField0;}public void setIntegerField0(Integer integerField0) {this.integerField0 = integerField0;}public Boolean getBooleanField0() {return booleanField0;}public void setBooleanField0(Boolean booleanField0) {this.booleanField0 = booleanField0;}public String getStringField1() {return stringField1;}public void setStringField1(String stringField1) {this.stringField1 = stringField1;}public Integer getIntegerField1() {return integerField1;}public void setIntegerField1(Integer integerField1) {this.integerField1 = integerField1;}public Boolean getBooleanField1() {return booleanField1;}public void setBooleanField1(Boolean booleanField1) {this.booleanField1 = booleanField1;}public String getStringField2() {return stringField2;}public void setStringField2(String stringField2) {this.stringField2 = stringField2;}public Integer getIntegerField2() {return integerField2;}public void setIntegerField2(Integer integerField2) {this.integerField2 = integerField2;}public Boolean getBooleanField2() {return booleanField2;}public void setBooleanField2(Boolean booleanField2) {this.booleanField2 = booleanField2;}public String getStringField3() {return stringField3;}public void setStringField3(String stringField3) {this.stringField3 = stringField3;}public Integer getIntegerField3() {return integerField3;}public void setIntegerField3(Integer integerField3) {this.integerField3 = integerField3;}public Boolean getBooleanField3() {return booleanField3;}public void setBooleanField3(Boolean booleanField3) {this.booleanField3 = booleanField3;}public String getStringField4() {return stringField4;}public void setStringField4(String stringField4) {this.stringField4 = stringField4;}public Integer getIntegerField4() {return integerField4;}public void setIntegerField4(Integer integerField4) {this.integerField4 = integerField4;}public Boolean getBooleanField4() {return booleanField4;}public void setBooleanField4(Boolean booleanField4) {this.booleanField4 = booleanField4;}public String getStringField5() {return stringField5;}public void setStringField5(String stringField5) {this.stringField5 = stringField5;}public Integer getIntegerField5() {return integerField5;}public void setIntegerField5(Integer integerField5) {this.integerField5 = integerField5;}public Boolean getBooleanField5() {return booleanField5;}public void setBooleanField5(Boolean booleanField5) {this.booleanField5 = booleanField5;}public String getStringField6() {return stringField6;}public void setStringField6(String stringField6) {this.stringField6 = stringField6;}public Integer getIntegerField6() {return integerField6;}public void setIntegerField6(Integer integerField6) {this.integerField6 = integerField6;}public Boolean getBooleanField6() {return booleanField6;}public void setBooleanField6(Boolean booleanField6) {this.booleanField6 = booleanField6;}public String getStringField7() {return stringField7;}public void setStringField7(String stringField7) {this.stringField7 = stringField7;}public String getStringField8() {return stringField8;}public void setStringField8(String stringField8) {this.stringField8 = stringField8;}public String getStringField9() {return stringField9;}public void setStringField9(String stringField9) {this.stringField9 = stringField9;}@Overridepublic String toString() {final StringBuilder sb = new StringBuilder();sb.append("SomeBigPojo");sb.append("{stringField0='").append(stringField0).append('\'');sb.append(", integerField0=").append(integerField0);sb.append(", booleanField0=").append(booleanField0);sb.append(", stringField1='").append(stringField1).append('\'');sb.append(", integerField1=").append(integerField1);sb.append(", booleanField1=").append(booleanField1);sb.append(", stringField2='").append(stringField2).append('\'');sb.append(", integerField2=").append(integerField2);sb.append(", booleanField2=").append(booleanField2);sb.append(", stringField3='").append(stringField3).append('\'');sb.append(", integerField3=").append(integerField3);sb.append(", booleanField3=").append(booleanField3);sb.append(", stringField4='").append(stringField4).append('\'');sb.append(", integerField4=").append(integerField4);sb.append(", booleanField4=").append(booleanField4);sb.append(", stringField5='").append(stringField5).append('\'');sb.append(", integerField5=").append(integerField5);sb.append(", booleanField5=").append(booleanField5);sb.append(", stringField6='").append(stringField6).append('\'');sb.append(", integerField6=").append(integerField6);sb.append(", booleanField6=").append(booleanField6);sb.append(", stringField7='").append(stringField7).append('\'');sb.append(", stringField8='").append(stringField8).append('\'');sb.append(", stringField9='").append(stringField9).append('\'');sb.append('}');return sb.toString();} }

現(xiàn)在看一下為了擺脫龐大構(gòu)造函數(shù)的使用而使用的builder類。 而且，您可以設(shè)置任何所需的內(nèi)容，而無需為不需要的字段輸入null。

SomeBigPojoBuilder.java

package pl.grzejszczak.marcin.junit.matchers.builder;import pl.grzejszczak.marcin.junit.matchers.pojo.SomeBigPojo;import static com.google.common.base.Preconditions.checkNotNull;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 21:08*/ public class SomeBigPojoBuilder {/** A field with some default value */private String stringField0 = "defaultValueForString0";/** A field with some default value */private Integer integerField0 = 100;/** A field with some default value */private Boolean booleanField0 = true;private String stringField1;private Integer integerField1;private Boolean booleanField1;private String stringField2;private Integer integerField2;private Boolean booleanField2;private String stringField3;private Integer integerField3;private Boolean booleanField3;private String stringField4;private Integer integerField4;private Boolean booleanField4;private String stringField5;private Integer integerField5;private Boolean booleanField5;private String stringField6;private Integer integerField6;private Boolean booleanField6;private String stringField7;private String stringField8;private String stringField9;public SomeBigPojoBuilder setStringField0(String stringField0) {this.stringField0 = stringField0;return this;}public SomeBigPojoBuilder setIntegerField0(Integer integerField0) {this.integerField0 = integerField0;return this;}public SomeBigPojoBuilder setBooleanField0(Boolean booleanField0) {this.booleanField0 = booleanField0;return this;}public SomeBigPojoBuilder setStringField1(String stringField1) {this.stringField1 = stringField1;return this;}public SomeBigPojoBuilder setIntegerField1(Integer integerField1) {this.integerField1 = integerField1;return this;}public SomeBigPojoBuilder setBooleanField1(Boolean booleanField1) {this.booleanField1 = booleanField1;return this;}public SomeBigPojoBuilder setStringField2(String stringField2) {this.stringField2 = stringField2;return this;}public SomeBigPojoBuilder setIntegerField2(Integer integerField2) {this.integerField2 = integerField2;return this;}public SomeBigPojoBuilder setBooleanField2(Boolean booleanField2) {this.booleanField2 = booleanField2;return this;}public SomeBigPojoBuilder setStringField3(String stringField3) {this.stringField3 = stringField3;return this;}public SomeBigPojoBuilder setIntegerField3(Integer integerField3) {this.integerField3 = integerField3;return this;}public SomeBigPojoBuilder setBooleanField3(Boolean booleanField3) {this.booleanField3 = booleanField3;return this;}public SomeBigPojoBuilder setStringField4(String stringField4) {this.stringField4 = stringField4;return this;}public SomeBigPojoBuilder setIntegerField4(Integer integerField4) {this.integerField4 = integerField4;return this;}public SomeBigPojoBuilder setBooleanField4(Boolean booleanField4) {this.booleanField4 = booleanField4;return this;}public SomeBigPojoBuilder setStringField5(String stringField5) {this.stringField5 = stringField5;return this;}public SomeBigPojoBuilder setIntegerField5(Integer integerField5) {this.integerField5 = integerField5;return this;}public SomeBigPojoBuilder setBooleanField5(Boolean booleanField5) {this.booleanField5 = booleanField5;return this;}public SomeBigPojoBuilder setStringField6(String stringField6) {this.stringField6 = stringField6;return this;}public SomeBigPojoBuilder setIntegerField6(Integer integerField6) {this.integerField6 = integerField6;return this;}public SomeBigPojoBuilder setBooleanField6(Boolean booleanField6) {this.booleanField6 = booleanField6;return this;}public SomeBigPojoBuilder setStringField7(String stringField7) {this.stringField7 = stringField7;return this;}public SomeBigPojoBuilder setStringField8(String stringField8) {this.stringField8 = stringField8;return this;}public SomeBigPojoBuilder setStringField9(String stringField9) {this.stringField9 = stringField9;return this;}/*** Some function checking the state of our POJO*/private void checkState(){checkNotNull(stringField1, "StringField1 must not be null!");}public SomeBigPojo createSomeBigPojoWithBuilder() {checkState();return new SomeBigPojo(stringField0, integerField0, booleanField0, stringField1, integerField1, booleanField1, stringField2, integerField2, booleanField2, stringField3, integerField3, booleanField3, stringField4, integerField4, booleanField4, stringField5, integerField5, booleanField5, stringField6, integerField6, booleanField6, stringField7, stringField8, stringField9);} }

看一下checkState函數(shù)，該函數(shù)驗證對象是否處于所需狀態(tài)。 這樣，如果某些條件不完整，我們可能不允許創(chuàng)建對象。 對于這種情況，我們使用番石榴的謂詞– checkNotNull方法。

請注意，Builder模式背后的概念是將對象的創(chuàng)建委托給Builder。 實際上，在純Builder設(shè)計模式實現(xiàn)中，我們將必須具有Director，對Builder的一些抽象以及這樣的Builder的具體實現(xiàn)。 在我們的例子中，我們簡化了這種模式–我使用了IntelliJ的重構(gòu)選項。 要使它看起來更好，可以做的是從POJO中刪除構(gòu)造函數(shù)，并僅通過setter傳遞值（這實際上是我在我的一個項目中所做的事情）。 現(xiàn)在讓我們看一些用法示例：

SomeServiceImpl.java

package pl.grzejszczak.marcin.junit.matchers.service;import org.slf4j.Logger; import org.slf4j.LoggerFactory; import pl.grzejszczak.marcin.junit.matchers.builder.SomeBigPojoBuilder; import pl.grzejszczak.marcin.junit.matchers.pojo.SomeBigPojo;import static java.lang.String.format;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 21:25*/ public class SomeServiceImpl implements SomeService {private static final Logger LOGGER = LoggerFactory.getLogger(SomeServiceImpl.class);/** Could be an abstraction of builders injected by a setter - possible to mock */private SomeBigPojoBuilder someBigPojoBuilder;/*** Hard to unit test*/@Overridepublic void someLogicForAPojoWithoutBuilder() {LOGGER.debug("SomeLogicForAPojoWithoutBuilder executed");SomeBigPojo someBigPojo = new SomeBigPojo("string", 1, false, "other string", 123, true, "something else", 321, false, "yet another string", 111, true, "something", 2, false, "More", 3, true, "String", 12, false, "some", "value", "ofString");// Any chance of knowing what is the value of stringField8 basing on the constructor?LOGGER.debug(format("StringField8 is equal [%s]%n", someBigPojo.getStringField8()));// Print the objectLOGGER.debug(someBigPojo.toString());}@Overridepublic void someLogicForAPojoWithBuilder() {LOGGER.debug("SomeLogicForAPojoWithBuilder executed");SomeBigPojo someBigPojo = someBigPojoBuilder.setStringField0("string").setIntegerField0(1).setBooleanField0(false).setStringField1("other string").setIntegerField1(123).setBooleanField1(true).setStringField2("something else").setIntegerField2(321).setBooleanField2(false).setStringField3("yet another string").setIntegerField3(111).setBooleanField3(false).setStringField4("something").setIntegerField4(2).setBooleanField4(false).setStringField5("More").setIntegerField5(3).setBooleanField5(true).setStringField6("String").setIntegerField6(12).setBooleanField6(false).setStringField7("some").setStringField8("value").setStringField9("ofString").createSomeBigPojoWithBuilder();// Looking at the builder now I guess it's obvious what the value of StringField8LOGGER.debug(format("StringField8 is equal [%s]%n", someBigPojo.getStringField8()));// Print the objectLOGGER.debug(someBigPojo.toString());}@Overridepublic void someLogicForAPojoWithBuilderBadArgument() {LOGGER.debug("someLogicForAPojoWithBuilderBadArgument executed");SomeBigPojo someBigPojo = someBigPojoBuilder.setStringField0("string").setIntegerField0(1).setBooleanField0(true).setIntegerField1(123).setBooleanField1(true).setStringField2("something else").setIntegerField2(321).setBooleanField2(false).setStringField3("yet another string").setIntegerField3(111).setBooleanField3(false).setStringField4("something").setIntegerField4(2).setBooleanField4(false).setStringField5("More").setIntegerField5(3).setBooleanField5(true).setStringField6("String").setIntegerField6(12).setBooleanField6(false).setStringField7("some").setStringField8("value").setStringField9("ofString").createSomeBigPojoWithBuilder();// Print the object - will we even see an outputLOGGER.debug(someBigPojo.toString());}public void setSomeBigPojoBuilder(SomeBigPojoBuilder someBigPojoBuilder) {this.someBigPojoBuilder = someBigPojoBuilder;} }

請注意，現(xiàn)在創(chuàng)建對象非常清楚，定義一個字段是否已設(shè)置也很容易。

讓我們繼續(xù)進行Hamcrest匹配器，這將幫助我們對班級進行單元測試。 我不會嘗試完成100％的完整代碼覆蓋-這篇文章的目的是說明Hamcrest Matchers如何成為您的單元測試的補充。 通常單元測試還不清楚，看起來像這樣：

SomeBigPojoBuilderNoMatchersAndNoRefactoringTest.java

package pl.grzejszczak.marcin.junit.matchers.builder;import org.junit.Before; import org.junit.Test; import pl.grzejszczak.marcin.junit.matchers.pojo.SomeBigPojo;import static junit.framework.Assert.assertTrue; import static org.apache.commons.lang.StringUtils.isNumeric; import static pl.grzejszczak.marcin.junit.matchers.pojo.SomePojoConstants.*;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 23:02*/ public class SomeBigPojoBuilderNoMatchersAndNoRefactoringTest {private SomeBigPojoBuilder objectUnderTest;@Beforepublic void setUp() {objectUnderTest = new SomeBigPojoBuilder();}@Testpublic void testCreateSomeBigPojoWithBuilder() throws Exception {SomeBigPojo someBigPojo = objectUnderTest.setBooleanField1(true).setStringField0("1").setStringField1("12").setStringField2("123").setStringField3("1234").setStringField4("12345").setStringField5("123456").setStringField6("1234567").setStringField7("12345678").setStringField8("123456789").setStringField9("1234567890").createSomeBigPojoWithBuilder();isPojoProperlyBuilt(someBigPojo);}@Test(expected = AssertionError.class)public void testCreateSomeBigPojoWithBuilderWrongFields() throws Exception {SomeBigPojo someBigPojo = objectUnderTest.setStringField0("0").setStringField1("Too long").createSomeBigPojoWithBuilder();isPojoProperlyBuilt(someBigPojo);}private void isPojoProperlyBuilt(SomeBigPojo someBigPojo) {assertTrue(someBigPojo.getStringField0().length() == STRING_FIELD_0_LENGTH);assertTrue(isNumeric(someBigPojo.getStringField0()));assertTrue(someBigPojo.getStringField1().length() == STRING_FIELD_1_LENGTH);assertTrue(isNumeric(someBigPojo.getStringField0()));assertTrue(someBigPojo.getStringField2().length() == STRING_FIELD_2_LENGTH);assertTrue(isNumeric(someBigPojo.getStringField0()));assertTrue(someBigPojo.getStringField3().length() == STRING_FIELD_3_LENGTH);assertTrue(isNumeric(someBigPojo.getStringField0()));assertTrue(someBigPojo.getStringField4().length() == STRING_FIELD_4_LENGTH);assertTrue(isNumeric(someBigPojo.getStringField0()));assertTrue(someBigPojo.getStringField5().length() == STRING_FIELD_5_LENGTH);assertTrue(someBigPojo.getStringField6().length() == STRING_FIELD_6_LENGTH);assertTrue(someBigPojo.getStringField7().length() == STRING_FIELD_7_LENGTH);assertTrue(someBigPojo.getStringField8().length() == STRING_FIELD_8_LENGTH);assertTrue(someBigPojo.getStringField9().length() == STRING_FIELD_9_LENGTH);} }

簡單的重構(gòu)可以使它們看起來更好……

SomeBigPojoBuilderNoMatchersTest.java

package pl.grzejszczak.marcin.junit.matchers.builder;import org.junit.Before; import org.junit.Test; import pl.grzejszczak.marcin.junit.matchers.pojo.SomeBigPojo;import static junit.framework.Assert.assertNotNull; import static junit.framework.Assert.assertTrue; import static org.apache.commons.lang.StringUtils.isNumeric; import static pl.grzejszczak.marcin.junit.matchers.pojo.SomePojoConstants.*;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 23:02*/ public class SomeBigPojoBuilderNoMatchersTest {private SomeBigPojoBuilder objectUnderTest;@Beforepublic void setUp() {objectUnderTest = new SomeBigPojoBuilder();}@Testpublic void testCreateSomeBigPojoWithBuilder() throws Exception {SomeBigPojo someBigPojo = objectUnderTest.setBooleanField1(true).setStringField0("1").setStringField1("12").setStringField2("123").setStringField3("1234").setStringField4("12345").setStringField5("123456").setStringField6("1234567").setStringField7("12345678").setStringField8("123456789").setStringField9("1234567890").createSomeBigPojoWithBuilder();isPojoProperlyBuilt(someBigPojo);}@Test(expected = AssertionError.class)public void testCreateSomeBigPojoWithBuilderWrongFields() throws Exception {SomeBigPojo someBigPojo = objectUnderTest.setStringField0("0").setStringField1("too long").createSomeBigPojoWithBuilder();isPojoProperlyBuilt(someBigPojo);}private void isPojoProperlyBuilt(SomeBigPojo someBigPojo) {isOfGivenLength(someBigPojo.getStringField0(), STRING_FIELD_0_LENGTH);isFieldOfNumericValue(someBigPojo.getStringField0());isOfGivenLength(someBigPojo.getStringField1(), STRING_FIELD_1_LENGTH);isFieldOfNumericValue(someBigPojo.getStringField0());isOfGivenLength(someBigPojo.getStringField2(), STRING_FIELD_2_LENGTH);isFieldOfNumericValue(someBigPojo.getStringField0());isOfGivenLength(someBigPojo.getStringField3(), STRING_FIELD_3_LENGTH);isFieldOfNumericValue(someBigPojo.getStringField0());isOfGivenLength(someBigPojo.getStringField4(), STRING_FIELD_4_LENGTH);isFieldOfNumericValue(someBigPojo.getStringField0());isOfGivenLength(someBigPojo.getStringField5(), STRING_FIELD_5_LENGTH);isOfGivenLength(someBigPojo.getStringField6(), STRING_FIELD_6_LENGTH);isOfGivenLength(someBigPojo.getStringField7(), STRING_FIELD_7_LENGTH);isOfGivenLength(someBigPojo.getStringField8(), STRING_FIELD_8_LENGTH);isOfGivenLength(someBigPojo.getStringField9(), STRING_FIELD_9_LENGTH);}private void isOfGivenLength(String pojo, final Integer expectedLength) {assertNotNull(pojo);assertTrue(expectedLength == pojo.length());}private void isFieldOfNumericValue(String field) {assertTrue(isNumeric(field));} }

看起來不錯，不是嗎？ 以及使用Matchers代替函數(shù)呢？

SomeBigPojoBuilderTest.kava

package pl.grzejszczak.marcin.junit.matchers.builder;import org.hamcrest.BaseMatcher; import org.hamcrest.Description; import org.hamcrest.Matcher; import org.junit.Before; import org.junit.Test; import pl.grzejszczak.marcin.junit.matchers.pojo.SomeBigPojo;import static java.lang.String.format; import static junit.framework.Assert.assertTrue; import static org.apache.commons.lang.StringUtils.isNumeric; import static org.junit.Assert.assertThat; import static pl.grzejszczak.marcin.junit.matchers.pojo.SomePojoConstants.*;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 23:02*/ public class SomeBigPojoBuilderTest {private SomeBigPojoBuilder objectUnderTest;@Beforepublic void setUp(){objectUnderTest = new SomeBigPojoBuilder();}@Testpublic void testCreateSomeBigPojoWithBuilder() throws Exception {SomeBigPojo someBigPojo = objectUnderTest.setBooleanField1(true).setStringField0("1").setStringField1("12").setStringField2("123").setStringField3("1234").setStringField4("12345").setStringField5("123456").setStringField6("1234567").setStringField7("12345678").setStringField8("123456789").setStringField9("1234567890").createSomeBigPojoWithBuilder();assertThat(someBigPojo, isPojoProperlyBuilt());}@Test(expected = AssertionError.class)public void testCreateSomeBigPojoWithBuilderWrongFields() throws Exception {SomeBigPojo someBigPojo = objectUnderTest.setStringField0("0").setStringField1("Too long").createSomeBigPojoWithBuilder();assertThat(someBigPojo, isPojoProperlyBuilt());}/*** Let us assume that there is a specific business case that we have to take into consideration regarding some particular field** @return*/private static Matcher isPojoProperlyBuilt() {return new BaseMatcher() {@Overridepublic boolean matches(Object o) {assertTrue(o instanceof SomeBigPojo);SomeBigPojo someBigPojo = (SomeBigPojo) o;assertThat(someBigPojo.getStringField0(), isOfGivenLength(STRING_FIELD_0_LENGTH));assertThat(someBigPojo.getStringField0(), isFieldOfNumericValue());assertThat(someBigPojo.getStringField1(), isOfGivenLength(STRING_FIELD_1_LENGTH));assertThat(someBigPojo.getStringField1(), isFieldOfNumericValue());assertThat(someBigPojo.getStringField2(), isOfGivenLength(STRING_FIELD_2_LENGTH));assertThat(someBigPojo.getStringField2(), isFieldOfNumericValue());assertThat(someBigPojo.getStringField3(), isOfGivenLength(STRING_FIELD_3_LENGTH));assertThat(someBigPojo.getStringField3(), isFieldOfNumericValue());assertThat(someBigPojo.getStringField4(), isOfGivenLength(STRING_FIELD_4_LENGTH));assertThat(someBigPojo.getStringField4(), isFieldOfNumericValue());assertThat(someBigPojo.getStringField5(), isOfGivenLength(STRING_FIELD_5_LENGTH));assertThat(someBigPojo.getStringField6(), isOfGivenLength(STRING_FIELD_6_LENGTH));assertThat(someBigPojo.getStringField7(), isOfGivenLength(STRING_FIELD_7_LENGTH));assertThat(someBigPojo.getStringField8(), isOfGivenLength(STRING_FIELD_8_LENGTH));assertThat(someBigPojo.getStringField9(), isOfGivenLength(STRING_FIELD_9_LENGTH));return true;}@Overridepublic void describeTo(Description description) {description.appendText("Lengths of fields are limited and the first 4 fields are numeric");}};}private static Matcher isOfGivenLength(final Integer expectedLength) {return new BaseMatcher() {public boolean matches(Object o) {assertTrue(o instanceof String);return expectedLength == String.valueOf(o).length();}public void describeTo(Description description) {description.appendText(format("String's length should be equal to [%d]", expectedLength));}};}private static Matcher isFieldOfNumericValue() {return new BaseMatcher() {public boolean matches(Object o) {assertTrue(o instanceof String);return isNumeric(String.valueOf(o));}public void describeTo(Description description) {description.appendText("The value of the field should be numeric");}};} }

以下主要方法執(zhí)行服務(wù)的功能：

package pl.grzejszczak.marcin.junit.matchers;import pl.grzejszczak.marcin.junit.matchers.builder.SomeBigPojoBuilder; import pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl;/*** Created with IntelliJ IDEA.* User: mgrzejszczak* Date: 03.01.13* Time: 22:38*/ public class MatcherMain {public static void main(String[] args){SomeServiceImpl someService = new SomeServiceImpl();someService.setSomeBigPojoBuilder(new SomeBigPojoBuilder());someService.someLogicForAPojoWithoutBuilder();someService.setSomeBigPojoBuilder(new SomeBigPojoBuilder());someService.someLogicForAPojoWithBuilder();someService.setSomeBigPojoBuilder(new SomeBigPojoBuilder());someService.someLogicForAPojoWithBuilderBadArgument();} }

日志是：

pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:27 SomeLogicForAPojoWithoutBuilder executed pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:30 StringField8 is equal [value]pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:32 SomeBigPojo{stringField0='string', integerField0=1, booleanField0=false, stringField1='other string', integerField1=123, booleanField1=true, stringField2='something else', integerField2=321, booleanField2=false, stringField3='yet another string', integerField3=111, booleanField3=true, stringField4='something', integerField4=2, booleanField4=false, stringField5='More', integerField5=3, booleanField5=true, stringField6='String', integerField6=12, booleanField6=false, stringField7='some', stringField8='value', stringField9='ofString'} pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:37 SomeLogicForAPojoWithBuilder executed pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:65 StringField8 is equal [value]pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:67 SomeBigPojo{stringField0='string', integerField0=1, booleanField0=false, stringField1='other string', integerField1=123, booleanField1=true, stringField2='something else', integerField2=321, booleanField2=false, stringField3='yet another string', integerField3=111, booleanField3=false, stringField4='something', integerField4=2, booleanField4=false, stringField5='More', integerField5=3, booleanField5=true, stringField6='String', integerField6=12, booleanField6=false, stringField7='some', stringField8='value', stringField9='ofString'} pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl:72 someLogicForAPojoWithBuilderBadArgument executed Exception in thread "main" java.lang.NullPointerException: StringField1 must not be null!at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:208)at pl.grzejszczak.marcin.junit.matchers.builder.SomeBigPojoBuilder.checkState(SomeBigPojoBuilder.java:166)at pl.grzejszczak.marcin.junit.matchers.builder.SomeBigPojoBuilder.createSomeBigPojoWithBuilder (SomeBigPojoBuilder.java:170)at pl.grzejszczak.marcin.junit.matchers.service.SomeServiceImpl.someLogicForAPojoWithBuilderBadArgument (SomeServiceImpl.java:73)at pl.grzejszczak.marcin.junit.matchers.MatcherMain.main(MatcherMain.java:23)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)at java.lang.reflect.Method.invoke(Method.java:597)at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)

在我看來，這看起來確實不錯。 那你呢？ 可在此處找到源代碼，代碼太多。

參考：來自我們的JCG合作伙伴 Marcin Grzejszczak的Hamcrest Matchers，Guava Predicate和Builder設(shè)計模式 ，該博客適用于上癮的編碼博客。

翻譯自: https://www.javacodegeeks.com/2013/04/hamcrest-matchers-guava-predicate-and-builder-design-pattern.html

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