javaee-servlet类源代码

程序员文章站 2022-04-23 17:50:42

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贴贴源代码，心理就好受多了，哎，犯贱吗！ javaee-servlet类源代码

博客分类： javaee ServletContextServletConfigServletGenericServletHttpServlet

ServletAPI 2.5的源代码

1.ServletContext就是我们经常说的application，不管是否常用，但总之是如雷贯耳。

package javax.servlet;

import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Enumeration;
import java.util.Set;

public abstract interface ServletContext
{
  public abstract String getContextPath();

  public abstract ServletContext getContext(String paramString);

  public abstract int getMajorVersion();

  public abstract int getMinorVersion();

  public abstract String getMimeType(String paramString);

  public abstract Set getResourcePaths(String paramString);

  public abstract URL getResource(String paramString)
    throws MalformedURLException;

  public abstract InputStream getResourceAsStream(String paramString);

  public abstract RequestDispatcher getRequestDispatcher(String paramString);

  public abstract RequestDispatcher getNamedDispatcher(String paramString);

  /**
   * @deprecated
   */
  public abstract Servlet getServlet(String paramString)
    throws javax.servlet.ServletException;

  /**
   * @deprecated
   */
  public abstract Enumeration getServlets();

  /**
   * @deprecated
   */
  public abstract Enumeration getServletNames();

  public abstract void log(String paramString);

  /**
   * @deprecated
   */
  public abstract void log(Exception paramException, String paramString);

  public abstract void log(String paramString, Throwable paramThrowable);

  public abstract String getRealPath(String paramString);

  public abstract String getServerInfo();

  public abstract String getInitParameter(String paramString);

  public abstract Enumeration getInitParameterNames();

  public abstract Object getAttribute(String paramString);

  public abstract Enumeration getAttributeNames();

  public abstract void setAttribute(String paramString, Object paramObject);

  public abstract void removeAttribute(String paramString);

  public abstract String getServletContextName();
}

2.接着是ServletConfig，用的真不多，就是从web.xml文件中提取参数。

web.xml

<!-- begin -->
	<servlet>
		<servlet-name>ConfigTestServlet</servlet-name>
		<servlet-class>org.it315.ConfigTestServlet</servlet-class>
		<init-param>
			<param-name>firstname</param-name>
			<param-value>zhangsan-张三</param-value>
		</init-param>
		<init-param>
			<param-name>lastname</param-name>
			<param-value>lisi-李四</param-value>
		</init-param>
	</servlet>
	<servlet-mapping>
		<servlet-name>ConfigTestServlet</servlet-name>
		<url-pattern>/configTest</url-pattern>
	</servlet-mapping>
	<!--end  -->

ServletConfig源代码

package javax.servlet;

import java.util.Enumeration;

public abstract interface ServletConfig
{
  public abstract String getServletName();

  public abstract ServletContext getServletContext();

  public abstract String getInitParameter(String paramString);

  public abstract Enumeration getInitParameterNames();
}

3.下面是Servlet的源代码（直接反编译来的，省的下载了），不管你知道不知道，你确一直在用

只有在首次访问时，容器发现内存中没有当前servlet，才创建servlet对象。 javaee-servlet类源代码

博客分类： javaee ServletContextServletConfigServletGenericServletHttpServlet 单例吗？

下面的init方法，在Servlet的整个生命周期内只被调用一次。

package javax.servlet;

import java.io.IOException;

public abstract interface Servlet
{
  public abstract void init(ServletConfig paramServletConfig)
    throws javax.servlet.ServletException;

  public abstract ServletConfig getServletConfig();

  public abstract void service(ServletRequest paramServletRequest, ServletResponse paramServletResponse)
    throws javax.servlet.ServletException, IOException;

  public abstract String getServletInfo();

  public abstract void destroy();
}

4.GenericServlet实现了Servlet, ServletConfig接口（Generic为通用之意）。同上，不管你知道不知道，你确一直在用

package javax.servlet;

import java.io.IOException;
import java.io.Serializable;
import java.util.Enumeration;
import java.util.ResourceBundle;

public abstract class GenericServlet
  implements Servlet, ServletConfig, Serializable
{
  private static final String LSTRING_FILE = "javax.servlet.LocalStrings";
  private static ResourceBundle lStrings = ResourceBundle.getBundle("javax.servlet.LocalStrings");
  private transient ServletConfig config;

  public void destroy()
  {
  }

  public String getInitParameter(String name)
  {
    ServletConfig sc = getServletConfig();
    if (sc == null) {
      throw new IllegalStateException(lStrings.getString("err.servlet_config_not_initialized"));
    }

    return sc.getInitParameter(name);
  }

  public Enumeration getInitParameterNames()
  {
    ServletConfig sc = getServletConfig();
    if (sc == null) {
      throw new IllegalStateException(lStrings.getString("err.servlet_config_not_initialized"));
    }

    return sc.getInitParameterNames();
  }

  public ServletConfig getServletConfig()
  {
    return this.config;
  }

  public ServletContext getServletContext()
  {
    ServletConfig sc = getServletConfig();
    if (sc == null) {
      throw new IllegalStateException(lStrings.getString("err.servlet_config_not_initialized"));
    }

    return sc.getServletContext();
  }

  public String getServletInfo()
  {
    return "";
  }

  public void init(ServletConfig config)
    throws javax.servlet.ServletException
  {
    this.config = config;
    init();
  }

  public void init()
    throws javax.servlet.ServletException
  {
  }

  public void log(String msg)
  {
    getServletContext().log(getServletName() + ": " + msg);
  }

  public void log(String message, Throwable t)
  {
    getServletContext().log(getServletName() + ": " + message, t);
  }

  public abstract void service(ServletRequest paramServletRequest, ServletResponse paramServletResponse)
    throws javax.servlet.ServletException, IOException;

  public String getServletName()
  {
    ServletConfig sc = getServletConfig();
    if (sc == null) {
      throw new IllegalStateException(lStrings.getString("err.servlet_config_not_initialized"));
    }

    return sc.getServletName();
  }
}

5.HttpServlet，到这，知道人就多了，呵呵。但除了doGet，doPost，service，其他从未用过。 javaee-servlet类源代码

博客分类： javaee ServletContextServletConfigServletGenericServletHttpServlet

package javax.servlet.http;

import java.io.IOException;
import java.io.Serializable;
import java.lang.reflect.Method;
import java.text.MessageFormat;
import java.util.Enumeration;
import java.util.ResourceBundle;
import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public abstract class HttpServlet extends GenericServlet
  implements Serializable
{
  private static final String METHOD_DELETE = "DELETE";
  private static final String METHOD_HEAD = "HEAD";
  private static final String METHOD_GET = "GET";
  private static final String METHOD_OPTIONS = "OPTIONS";
  private static final String METHOD_POST = "POST";
  private static final String METHOD_PUT = "PUT";
  private static final String METHOD_TRACE = "TRACE";
  private static final String HEADER_IFMODSINCE = "If-Modified-Since";
  private static final String HEADER_LASTMOD = "Last-Modified";
  private static final String LSTRING_FILE = "javax.servlet.http.LocalStrings";
  private static ResourceBundle lStrings = ResourceBundle.getBundle("javax.servlet.http.LocalStrings");

  protected void doGet(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException
  {
    String protocol = req.getProtocol();
    String msg = lStrings.getString("http.method_get_not_supported");
    if (protocol.endsWith("1.1"))
      resp.sendError(405, msg);
    else
      resp.sendError(400, msg);
  }

  protected long getLastModified(HttpServletRequest req)
  {
    return -1L;
  }

  protected void doHead(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException
  {
    NoBodyResponse response = new NoBodyResponse(resp);

    doGet(req, response);
    response.setContentLength();
  }

  protected void doPost(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException
  {
    String protocol = req.getProtocol();
    String msg = lStrings.getString("http.method_post_not_supported");
    if (protocol.endsWith("1.1"))
      resp.sendError(405, msg);
    else
      resp.sendError(400, msg);
  }

  protected void doPut(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException
  {
    String protocol = req.getProtocol();
    String msg = lStrings.getString("http.method_put_not_supported");
    if (protocol.endsWith("1.1"))
      resp.sendError(405, msg);
    else
      resp.sendError(400, msg);
  }

  protected void doDelete(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException
  {
    String protocol = req.getProtocol();
    String msg = lStrings.getString("http.method_delete_not_supported");
    if (protocol.endsWith("1.1"))
      resp.sendError(405, msg);
    else
      resp.sendError(400, msg);
  }

  private Method[] getAllDeclaredMethods(Class c)
  {
    if (c.equals(HttpServlet.class)) {
      return null;
    }

    Method[] parentMethods = getAllDeclaredMethods(c.getSuperclass());
    Method[] thisMethods = c.getDeclaredMethods();

    if ((parentMethods != null) && (parentMethods.length > 0)) {
      Method[] allMethods = new Method[parentMethods.length + thisMethods.length];

      System.arraycopy(parentMethods, 0, allMethods, 0, parentMethods.length);

      System.arraycopy(thisMethods, 0, allMethods, parentMethods.length, thisMethods.length);

      thisMethods = allMethods;
    }

    return thisMethods;
  }

  protected void doOptions(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException
  {
    Method[] methods = getAllDeclaredMethods(getClass());

    boolean ALLOW_GET = false;
    boolean ALLOW_HEAD = false;
    boolean ALLOW_POST = false;
    boolean ALLOW_PUT = false;
    boolean ALLOW_DELETE = false;
    boolean ALLOW_TRACE = true;
    boolean ALLOW_OPTIONS = true;

    for (int i = 0; i < methods.length; ++i) {
      Method m = methods[i];

      if (m.getName().equals("doGet")) {
        ALLOW_GET = true;
        ALLOW_HEAD = true;
      }
      if (m.getName().equals("doPost"))
        ALLOW_POST = true;
      if (m.getName().equals("doPut"))
        ALLOW_PUT = true;
      if (m.getName().equals("doDelete"))
        ALLOW_DELETE = true;

    }

    String allow = null;
    if ((ALLOW_GET) && 
      (allow == null)) allow = "GET";
    if (ALLOW_HEAD)
      if (allow == null) allow = "HEAD";
      else allow = allow + ", HEAD";
    if (ALLOW_POST)
      if (allow == null) allow = "POST";
      else allow = allow + ", POST";
    if (ALLOW_PUT)
      if (allow == null) allow = "PUT";
      else allow = allow + ", PUT";
    if (ALLOW_DELETE)
      if (allow == null) allow = "DELETE";
      else allow = allow + ", DELETE";
    if (ALLOW_TRACE)
      if (allow == null) allow = "TRACE";
      else allow = allow + ", TRACE";
    if (ALLOW_OPTIONS)
      if (allow == null) allow = "OPTIONS";
      else allow = allow + ", OPTIONS";

    resp.setHeader("Allow", allow);
  }

  protected void doTrace(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException
  {
    String CRLF = "\r\n";
    String responseString = "TRACE " + req.getRequestURI() + " " + req.getProtocol();

    Enumeration reqHeaderEnum = req.getHeaderNames();

    while (reqHeaderEnum.hasMoreElements()) {
      String headerName = (String)reqHeaderEnum.nextElement();
      responseString = responseString + CRLF + headerName + ": " + req.getHeader(headerName);
    }

    responseString = responseString + CRLF;

    int responseLength = responseString.length();

    resp.setContentType("message/http");
    resp.setContentLength(responseLength);
    ServletOutputStream out = resp.getOutputStream();
    out.print(responseString);
    out.close();
  }

  protected void service(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException
  {
    long lastModified;
    String method = req.getMethod();

    if (method.equals("GET")) {
      lastModified = getLastModified(req);
      if (lastModified == -1L)
      {
        doGet(req, resp);
      } else {
        long ifModifiedSince = req.getDateHeader("If-Modified-Since");
        if (ifModifiedSince < lastModified / 1000L * 1000L)
        {
          maybeSetLastModified(resp, lastModified);
          doGet(req, resp);
        } else {
          resp.setStatus(304);
        }
      }
    }
    else if (method.equals("HEAD")) {
      lastModified = getLastModified(req);
      maybeSetLastModified(resp, lastModified);
      doHead(req, resp);
    }
    else if (method.equals("POST")) {
      doPost(req, resp);
    }
    else if (method.equals("PUT")) {
      doPut(req, resp);
    }
    else if (method.equals("DELETE")) {
      doDelete(req, resp);
    }
    else if (method.equals("OPTIONS")) {
      doOptions(req, resp);
    }
    else if (method.equals("TRACE")) {
      doTrace(req, resp);
    }
    else
    {
      String errMsg = lStrings.getString("http.method_not_implemented");
      Object[] errArgs = new Object[1];
      errArgs[0] = method;
      errMsg = MessageFormat.format(errMsg, errArgs);

      resp.sendError(501, errMsg);
    }
  }

  private void maybeSetLastModified(HttpServletResponse resp, long lastModified)
  {
    if (resp.containsHeader("Last-Modified"))
      return;
    if (lastModified >= -3069086688014761984L)
      resp.setDateHeader("Last-Modified", lastModified);
  }

  public void service(ServletRequest req, ServletResponse res)
    throws ServletException, IOException
  {
    HttpServletRequest request;
    HttpServletResponse response;
    try
    {
      request = (HttpServletRequest)req;
      response = (HttpServletResponse)res;
    } catch (ClassCastException e) {
      throw new ServletException("non-HTTP request or response");
    }
    service(request, response);
  }
}

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javaee-servlet类源代码

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