顶级接口:Servlet:
package javax.servlet;
import java.io.IOException;
public interface Servlet {
public void init(ServletConfig config) throws ServletException;
public ServletConfig getServletConfig();
public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException;
public String getServletInfo();
public void destroy();
}
GenericServlet抽象类:
package javax.servlet;
import java.io.IOException;
import java.util.Enumeration;
public abstract class GenericServlet implements Servlet, ServletConfig,
java.io.Serializable {
private static final long serialVersionUID = 1L;
private transient ServletConfig config;
@Override
public void init(ServletConfig config) throws ServletException {
this.config = config;
this.init();
}
public void init() throws ServletException {
// NOOP by default
}
@Override
public abstract void service(ServletRequest req, ServletResponse res) throws ServletException, IOException;
@Override
public ServletConfig getServletConfig() {
return config;
}
@Override
public String getServletInfo() {
return "";
}
@Override
public void destroy() {
// NOOP by default
}
public GenericServlet() {
// NOOP
}
@Override
public String getInitParameter(String name) {
return getServletConfig().getInitParameter(name);
}
@Override
public Enumeration<String> getInitParameterNames() {
return getServletConfig().getInitParameterNames();
}
public void log(String msg) {
getServletContext().log(getServletName() + ": " + msg);
}
public void log(String message, Throwable t) {
getServletContext().log(getServletName() + ": " + message, t);
}
@Override
public String getServletName() {
return config.getServletName();
}
@Override
public ServletContext getServletContext() {
return getServletConfig().getServletContext();
}
}
HttpServlet:
package javax.servlet.http;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.Method;
import java.text.MessageFormat;
import java.util.Enumeration;
import java.util.ResourceBundle;
import javax.servlet.DispatcherType;
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 {
private static final long serialVersionUID = 1L;
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(LSTRING_FILE);
public HttpServlet() {
// NOOP
}
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(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
} else {
resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
}
}
protected long getLastModified(HttpServletRequest req) {
return -1;
}
protected void doHead(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
if (DispatcherType.INCLUDE.equals(req.getDispatcherType())) {
doGet(req, resp);
} else {
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(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
} else {
resp.sendError(HttpServletResponse.SC_BAD_REQUEST, 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(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
} else {
resp.sendError(HttpServletResponse.SC_BAD_REQUEST, 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(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
} else {
resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
}
}
private static Method[] getAllDeclaredMethods(Class<?> c) {
if (c.equals(javax.servlet.http.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(this.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=METHOD_GET;
if (ALLOW_HEAD)
if (allow==null) allow=METHOD_HEAD;
else allow += ", " + METHOD_HEAD;
if (ALLOW_POST)
if (allow==null) allow=METHOD_POST;
else allow += ", " + METHOD_POST;
if (ALLOW_PUT)
if (allow==null) allow=METHOD_PUT;
else allow += ", " + METHOD_PUT;
if (ALLOW_DELETE)
if (allow==null) allow=METHOD_DELETE;
else allow += ", " + METHOD_DELETE;
if (ALLOW_TRACE)
if (allow==null) allow=METHOD_TRACE;
else allow += ", " + METHOD_TRACE;
if (ALLOW_OPTIONS)
if (allow==null) allow=METHOD_OPTIONS;
else allow += ", " + METHOD_OPTIONS;
resp.setHeader("Allow", allow);
}
protected void doTrace(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException
{
int responseLength;
String CRLF = "\r\n";
StringBuilder buffer = new StringBuilder("TRACE ").append(req.getRequestURI())
.append(" ").append(req.getProtocol());
Enumeration<String> reqHeaderEnum = req.getHeaderNames();
while( reqHeaderEnum.hasMoreElements() ) {
String headerName = reqHeaderEnum.nextElement();
buffer.append(CRLF).append(headerName).append(": ")
.append(req.getHeader(headerName));
}
buffer.append(CRLF);
responseLength = buffer.length();
resp.setContentType("message/http");
resp.setContentLength(responseLength);
ServletOutputStream out = resp.getOutputStream();
out.print(buffer.toString());
out.close();
return;
}
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String method = req.getMethod();
if (method.equals(METHOD_GET)) {
long lastModified = getLastModified(req);
if (lastModified == -1) {
doGet(req, resp);
} else {
long ifModifiedSince;
try {
ifModifiedSince = req.getDateHeader(HEADER_IFMODSINCE);
} catch (IllegalArgumentException iae) {
ifModifiedSince = -1;
}
if (ifModifiedSince < (lastModified / 1000 * 1000)) {
maybeSetLastModified(resp, lastModified);
doGet(req, resp);
} else {
resp.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
}
}
} else if (method.equals(METHOD_HEAD)) {
long lastModified = getLastModified(req);
maybeSetLastModified(resp, lastModified);
doHead(req, resp);
} else if (method.equals(METHOD_POST)) {
doPost(req, resp);
} else if (method.equals(METHOD_PUT)) {
doPut(req, resp);
} else if (method.equals(METHOD_DELETE)) {
doDelete(req, resp);
} else if (method.equals(METHOD_OPTIONS)) {
doOptions(req,resp);
} else if (method.equals(METHOD_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(HttpServletResponse.SC_NOT_IMPLEMENTED, errMsg);
}
}
private void maybeSetLastModified(HttpServletResponse resp,
long lastModified) {
if (resp.containsHeader(HEADER_LASTMOD))
return;
if (lastModified >= 0)
resp.setDateHeader(HEADER_LASTMOD, lastModified);
}
@Override
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);
}
}
class NoBodyResponse extends HttpServletResponseWrapper {
private NoBodyOutputStream noBody;
private PrintWriter writer;
private boolean didSetContentLength;
NoBodyResponse(HttpServletResponse r) {
super(r);
noBody = new NoBodyOutputStream();
}
void setContentLength() {
if (!didSetContentLength) {
if (writer != null) {
writer.flush();
}
super.setContentLength(noBody.getContentLength());
}
}
@Override
public void setContentLength(int len) {
super.setContentLength(len);
didSetContentLength = true;
}
@Override
public void setHeader(String name, String value) {
super.setHeader(name, value);
checkHeader(name);
}
@Override
public void addHeader(String name, String value) {
super.addHeader(name, value);
checkHeader(name);
}
@Override
public void setIntHeader(String name, int value) {
super.setIntHeader(name, value);
checkHeader(name);
}
@Override
public void addIntHeader(String name, int value) {
super.addIntHeader(name, value);
checkHeader(name);
}
private void checkHeader(String name) {
if ("content-length".equalsIgnoreCase(name)) {
didSetContentLength = true;
}
}
@Override
public ServletOutputStream getOutputStream() throws IOException {
return noBody;
}
@Override
public PrintWriter getWriter() throws UnsupportedEncodingException {
if (writer == null) {
OutputStreamWriter w;
w = new OutputStreamWriter(noBody, getCharacterEncoding());
writer = new PrintWriter(w);
}
return writer;
}
}
class NoBodyOutputStream extends ServletOutputStream {
private static final String LSTRING_FILE =
"javax.servlet.http.LocalStrings";
private static ResourceBundle lStrings =
ResourceBundle.getBundle(LSTRING_FILE);
private int contentLength = 0;
NoBodyOutputStream() {
}
int getContentLength() {
return contentLength;
}
@Override
public void write(int b) {
contentLength++;
}
@Override
public void write(byte buf[], int offset, int len) throws IOException {
if (buf == null) {
throw new NullPointerException(
lStrings.getString("err.io.nullArray"));
}
if (offset < 0 || len < 0 || offset+len > buf.length) {
String msg = lStrings.getString("err.io.indexOutOfBounds");
Object[] msgArgs = new Object[3];
msgArgs[0] = Integer.valueOf(offset);
msgArgs[1] = Integer.valueOf(len);
msgArgs[2] = Integer.valueOf(buf.length);
msg = MessageFormat.format(msg, msgArgs);
throw new IndexOutOfBoundsException(msg);
}
contentLength += len;
}
}
标签:String,resp,req,private,源码,void,Servlet,public
From: https://blog.51cto.com/u_14121041/6416349