深入分析Java中webwork的文件上传机制 - 编程入门网

深入分析Java中webwork的文件上传机制

点击上传按钮后，webwork的程序流如下：

step 1）进入ServletDispatcher.service

public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException { ........ request = wrapRequest(request); ......... }

step2)进入ServletDispatcher.wrapRequest

protected HttpServletRequest wrapRequest(HttpServletRequest request) throws IOException { ........................ if (MultiPartRequest.isMultiPart(request)) { request = new MultiPartRequestWrapper(request, getSaveDir(), getMaxSize()); } return request; }

step3)进入MultiPartRequestWrapper的构造方法

public MultiPartRequestWrapper(HttpServletRequest request, String saveDir, int maxSize) throws IOException { ..................... //step3.1)获取webwork.preperties配置的parser String parser = ""; parser = Configuration.getString("webwork.multipart.parser"); // If it''s not set, use Pell if (parser.equals("")) { log.warn("Property webwork.multipart.parser not set." + " Using com.opensymphony.webwork.dispatcher.multipart.PellMultiPartRequest"); parser = "com.opensymphony.webwork.dispatcher.multipart.PellMultiPartRequest"; } // legacy support for old style property values else if (parser.equals("pell")) { parser = "com.opensymphony.webwork.dispatcher.multipart.PellMultiPartRequest"; } else if (parser.equals("cos")) { parser = "com.opensymphony.webwork.dispatcher.multipart.CosMultiPartRequest"; } else if (parser.equals("jakarta")) { parser = "com.opensymphony.webwork.dispatcher.multipart.JakartaMultiPartRequest"; } //step3.2)获取后通过反射实例化parser try { Class baseClazz = com.opensymphony.webwork.dispatcher.multipart.MultiPartRequest.class; Class clazz = Class.forName(parser); // make sure it extends MultiPartRequest if (!baseClazz.isAssignableFrom(clazz)) { addError("Class ''" + parser + "'' does not extend MultiPartRequest"); return; } // get the constructor Constructor ctor = clazz.getDeclaredConstructor(new Class[]{ Class.forName("javax.servlet.http.HttpServletRequest"), java.lang.String.class, int.class }); // build the parameter list Object[] parms = new Object[]{ request, saveDir, new Integer(maxSize) }; // instantiate it multi = (MultiPartRequest) ctor.newInstance(parms); ................................................. }

深入分析Java中webwork的文件上传机制(2)

step4 进入JakartaMultiPartRequest的构造方法（在webwork配置的parser是Jakarta所以进入了这个方法，如果你配置不同的parser回进入不同的parser

public JakartaMultiPartRequest(HttpServletRequest servletRequest, String saveDir, int maxSize) throws IOException { //设置保存参数 DiskFileUpload upload = new DiskFileUpload(); // we must store all uploads on disk because the ww multipart API is missing streaming // capabilities upload.setSizeThreshold(0); upload.setSizeMax(maxSize); if (saveD

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