看這篇文章：http://tutorials.jenkov.com/java-exception-handling/exception-handling-templates.html

再錄一下：

一個(gè)異常捕獲后，在?finally?里中再捕獲異常，拋出異常會(huì)覆蓋先前的異常信息，所以需要清晰的判斷每個(gè)可能的異常，如此不會(huì)遺漏被覆蓋的異常。如果代碼復(fù)雜，異常判斷是一鍵冗余的事情，所以會(huì)用模板的方式來(lái)簡(jiǎn)化工作，減少出錯(cuò)。

其實(shí)就是講一個(gè)共通的代碼如何更加優(yōu)雅的公用。

 Input       input            = null;IOException processException = null;try{input = new FileInputStream(fileName);//...process input stream...} catch (IOException e) {processException = e;} finally {if(input != null){try {input.close();} catch(IOException e){if(processException != null){throw new MyException(processException, e,"Error message..." +fileName);} else {throw new MyException(e,"Error closing InputStream for file " +fileName;}}}if(processException != null){throw new MyException(processException,"Error processing InputStream for file " +fileName;}

?

模板模式：

public abstract class InputStreamProcessingTemplate {public void process(String fileName){IOException processException = null;InputStream input = null;try{input = new FileInputStream(fileName);doProcess(input);} catch (IOException e) {processException = e;} finally {if(input != null){try {input.close();} catch(IOException e){if(processException != null){throw new MyException(processException, e,"Error message..." +fileName);} else {throw new MyException(e,"Error closing InputStream for file " +fileName;}}}if(processException != null){throw new MyException(processException,"Error processing InputStream for file " +fileName;}}//override this method in a subclass, to process the stream.public abstract void doProcess(InputStream input) throws IOException;
}

調(diào)用：

  new InputStreamProcessingTemplate(){public void doProcess(InputStream input) throws IOException{int inChar = input.read();while(inChar !- -1){//do something with the chars...
            }}}.process("someFile.txt");

?

接口實(shí)現(xiàn)的辦法：

public interface InputStreamProcessor {public void process(InputStream input) throws IOException;
}public class InputStreamProcessingTemplate {public void process(String fileName, InputStreamProcessor processor){IOException processException = null;InputStream input = null;try{input = new FileInputStream(fileName);processor.process(input);} catch (IOException e) {processException = e;} finally {if(input != null){try {input.close();} catch(IOException e){if(processException != null){throw new MyException(processException, e,"Error message..." +fileName;} else {throw new MyException(e,"Error closing InputStream for file " +fileName);}}}if(processException != null){throw new MyException(processException,"Error processing InputStream for file " +fileName;}}
}

調(diào)用：

new InputStreamProcessingTemplate().process("someFile.txt", new InputStreamProcessor(){public void process(InputStream input) throws IOException{int inChar = input.read();while(inChar !- -1){//do something with the chars...
                }}});

?

靜態(tài)模板：

public class InputStreamProcessingTemplate {public static void process(String fileName,InputStreamProcessor processor){IOException processException = null;InputStream input = null;try{input = new FileInputStream(fileName);processor.process(input);} catch (IOException e) {processException = e;} finally {if(input != null){try {input.close();} catch(IOException e){if(processException != null){throw new MyException(processException, e,"Error message..." +fileName);} else {throw new MyException(e,"Error closing InputStream for file " +fileName;}}}if(processException != null){throw new MyException(processException,"Error processing InputStream for file " +fileName;}}
}

?

調(diào)用：

 InputStreamProcessingTemplate.process("someFile.txt",new InputStreamProcessor(){public void process(InputStream input) throws IOException{int inChar = input.read();while(inChar !- -1){//do something with the chars...
                }}});

?

轉(zhuǎn)載于:https://www.cnblogs.com/killbug/p/4080606.html

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