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<h2>4.2 生成Return操作</h2> <p>這一節(jié)我們將講述如何生成return操作，我們將生成如下代碼：</p> <div style="padding-bottom: 0px; margin: 0px; padding-left: 0px; padding-right: 0px; display: inline; float: none; padding-top: 0px" id="scid:9D7513F9-C04C-4721-824A-2B34F0212519:0041272d-4ecf-4039-a991-b5323856859d" class="wlWriterEditableSmartContent"><pre class="brush: java; gutter: true; first-line: 1; tab-size: 4; toolbar: true; width: 964px; height: 263px;" style=" width: 964px; height: 263px;overflow: auto;">package generated.operators;

import java.io.PrintStream;

public class ReturnOperatorGenerateExample { public static String commonMethod() { return "I'm from commonMethod"; }

public static void main(String[] args) { System.out.println(commonMethod()); } }</pre><!-- Code inserted with Steve Dunn's Windows Live Writer Code Formatter Plugin. http://dunnhq.com --></div>

<p>這段代碼的兩個(gè)方法的返回類型分別是String和void，對(duì)應(yīng)的ASMSupport的代碼如下：</p>

<p> <div style="padding-bottom: 0px; margin: 0px; padding-left: 0px; padding-right: 0px; display: inline; float: none; padding-top: 0px" id="scid:9D7513F9-C04C-4721-824A-2B34F0212519:74055c8b-f8a1-4671-a4d4-5f47171f957e" class="wlWriterEditableSmartContent"><pre class="brush: java; gutter: true; first-line: 1; tab-size: 4; toolbar: true; width: 964px; height: 471px;" style=" width: 964px; height: 471px;overflow: auto;">public static void main(String[] args) { ClassCreator creator = new ClassCreator(Opcodes.V1_5, Opcodes.ACC_PUBLIC , &quot;generated.operators.ReturnOperatorGenerateExample&quot;, null, null);

/* * 有返回類型的方法*/ creator.createStaticMethod(&quot;commonMethod&quot;, null, null, AClass.STRING_ACLASS, null, Opcodes.ACC_PUBLIC, new StaticMethodBody(){@Overridepublic void generateBody(LocalVariable... argus) {runReturn(Value.value(&quot;I'm from commonMethod&quot;));} });/* * 無(wú)返回類型的方法*/ creator.createStaticMethod(&quot;main&quot;, new AClass[]{AClassFactory.getProductClass(String[].class)}, new String[]{&quot;args&quot;}, null, null,Opcodes.ACC_PUBLIC + Opcodes.ACC_STATIC, new StaticMethodBody(){@Overridepublic void generateBody(LocalVariable... argus) {invoke(systemOut, &quot;println&quot;, invokeStatic(getMethodOwner(), &quot;commonMethod&quot;));runReturn();} }); generate(creator);

}</pre><!-- Code inserted with Steve Dunn's Windows Live Writer Code Formatter Plugin. http://dunnhq.com --></div>

</p>

<p>這里我們主要關(guān)注的是runReturn(Value.value(&quot;I'm from commonMethod&quot;))和runReturn(),前者是非void的，參數(shù)就是我們方法需要返回的值，后者就是直接return，沒(méi)有返回值。</p>

轉(zhuǎn)載于:https://my.oschina.net/wensiqun/blog/140070

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