/**
* Defines an object to provide client request information to a servlet. The
* servlet container creates a <code>ServletRequest</code> object and passes
* it as an argument to the servlet's <code>service</code> method.
* <p>A <code>ServletRequest</code> object provides data including
* parameter name and values, attributes, and an input stream.
* Interfaces that extend <code>ServletRequest</code> can provide
* additional protocol-specific data (for example, HTTP data is
* provided by {@link javax.servlet.http.HttpServletRequest}.
* @author Various
* @version $Version$
* @see javax.servlet.http.HttpServletRequest
*/
//定义一个对象将客户端的请求信息传递给Servlet，Servlet 容器会创建一个ServletRequest对象并床的它的参数给Servlet的service方法
//一个ServletRequest对象提供的数据包括参数name和value，属性和一个输入流
//一个接口继承了ServletRequest会提供额外的特别的协议数据
public interface ServletRequest {
/**
* Returns the value of the named attribute as an <code>Object</code>,
* or <code>null</code> if no attribute of the given name exists.
* <p> Attributes can be set two ways. The servlet container may set
* attributes to make available custom information about a request.
* For example, for requests made using HTTPS, the attribute
* <code>javax.servlet.request.X509Certificate</code> can be used to
* retrieve information on the certificate of the client. Attributes
* can also be set programatically using
* {@link ServletRequest#setAttribute}. This allows information to be
* embedded into a request before a {@link RequestDispatcher} call.
* <p>Attribute names should follow the same conventions as package
* names. This specification reserves names matching <code>java.*</code>,
* <code>javax.*</code>, and <code>sun.*</code>.
* @param name a <code>String</code> specifying the name of the attribute
* @return an <code>Object</code> containing the value of the attribute, or <code>null</code> if
* the attribute does not exist
*/
//获得name的属性对象，
public Object getAttribute(String name);
/**
* Returns an <code>Enumeration</code> containing the
* names of the attributes available to this request.
* This method returns an empty <code>Enumeration</code>
* if the request has no attributes available to it.
* @return an <code>Enumeration</code> of strings
* containing the names of the request's attributes
*/
//返回一个枚举包含了这个Request有效的属性的name
public Enumeration getAttributeNames();
/**
* Returns the name of the character encoding used in the body of this
* request. This method returns <code>null</code> if the request
* does not specify a character encoding
* @return a <code>String</code> containing the name of
* the character encoding, or <code>null</code>if the request does not specify a character encoding
*/
//返回这个Request请求的body所使用的字符类型
public String getCharacterEncoding();
/**
* Overrides the name of the character encoding used in the body of this
* request. This method must be called prior to reading request parameters
* or reading input using getReader().
* @param env a <code>String</code> containing the name of the character encoding.
* @throws java.io.UnsupportedEncodingException if this is not a valid encoding
*/
//覆盖这个请求body中的字符类型
public void setCharacterEncoding(String env) throws java.io.UnsupportedEncodingException;
/**
* Returns the length, in bytes, of the request body
* and made available by the input stream, or -1 if the
* length is not known. For HTTP servlets, same as the value
* of the CGI variable CONTENT_LENGTH.
* @return an integer containing the length of the
* request body or -1 if the length is not known
*/
//返回输入流的长度
public int getContentLength();
/**
* Returns the MIME type of the body of the request, or
* <code>null</code> if the type is not known. For HTTP servlets,
* same as the value of the CGI variable CONTENT_TYPE.
*
* @return a <code>String</code> containing the name
* of the MIME type of
* the request, or null if the type is not known
*
*/
//返回请求体中的文件类型
public String getContentType();
/**
* Retrieves the body of the request as binary data using
* a {@link ServletInputStream}. Either this method or
* {@link #getReader} may be called to read the body, not both.
* @return a {@link ServletInputStream} object containing the body of the request
* @exception IllegalStateException if the {@link #getReader} method has already been called for this request
* @exception IOException if an input or output exception occurred
*/
//检索请求体中的二进制数据
public ServletInputStream getInputStream() throws IOException;
/**
* Returns the value of a request parameter as a <code>String</code>,
* or <code>null</code> if the parameter does not exist. Request parameters
* are extra information sent with the request. For HTTP servlets,
* parameters are contained in the query string or posted form data.
* <p>You should only use this method when you are sure the
* parameter has only one value. If the parameter might have
* more than one value, use {@link #getParameterValues}.
* <p>If you use this method with a multivalued
* parameter, the value returned is equal to the first value
* in the array returned by <code>getParameterValues</code>.
* <p>If the parameter data was sent in the request body, such as occurs
* with an HTTP POST request, then reading the body directly via {@link
* #getInputStream} or {@link #getReader} can interfere
* with the execution of this method.
* @param name a <code>String</code> specifying the
* name of the parameter
* @return a <code>String</code> representing the
* single value of the parameter
* @see #getParameterValues
*/
//返回参数name的值，当parameter有一个值时，有多个值时使用getParameterValues
public String getParameter(String name);
/**
* Returns an <code>Enumeration</code> of <code>String</code>
* objects containing the names of the parameters contained
* in this request. If the request has
* no parameters, the method returns an
* empty <code>Enumeration</code>.
* @return an <code>Enumeration</code> of <code>String</code>
* objects, each <code>String</code> containing
* the name of a request parameter; or an
* empty <code>Enumeration</code> if the
* request has no parameters
*/
//返回所有参数的name作为一个枚举
public Enumeration getParameterNames();
/**
* Returns an array of <code>String</code> objects containing
* all of the values the given request parameter has, or
* <code>null</code> if the parameter does not exist.
* <p>If the parameter has a single value, the array has a length
* of 1.
* @param name a <code>String</code> containing the name of
* the parameter whose value is requested
* @return an array of <code>String</code> objects
* containing the parameter's values
* @see #getParameter
*
*/
//返回name参数的所有值
public String[] getParameterValues(String name);
/** Returns a java.util.Map of the parameters of this request.
* Request parameters
* are extra information sent with the request. For HTTP servlets,
* parameters are contained in the query string or posted form data.
* @return an immutable java.util.Map containing parameter names as
* keys and parameter values as map values. The keys in the parameter
* map are of type String. The values in the parameter map are of type
* String array.
*/
public Map getParameterMap();
/**
* Returns the name and version of the protocol the request uses
* in the form <i>protocol/majorVersion.minorVersion</i>, for
* example, HTTP/1.1. For HTTP servlets, the value
* returned is the same as the value of the CGI variable
* <code>SERVER_PROTOCOL</code>.
*/
//返回请求协议的name和版本
public String getProtocol();
/**
* Returns the name of the scheme used to make this request, for example,
* <code>http</code>, <code>https</code>, or <code>ftp</code>.
* Different schemes have different rules for constructing URLs,
* as noted in RFC 1738.
* @return a <code>String</code> containing the name
* of the scheme used to make this request
*/
//返回协议名称 http、https、ftp
public String getScheme();
/**
* Returns the host name of the server to which the request was sent.
* It is the value of the part before ":" in the <code>Host</code>
* header value, if any, or the resolved server name, or the server IP address.
* @return a <code>String</code> containing the name
*/
//获得请求发送的服务器名称
public String getServerName();
/**
* Returns the port number to which the request was sent.
* It is the value of the part after ":" in the <code>Host</code>
* header value, if any, or the server port where the client connection
* was accepted on.
* @return an integer specifying the port number
*/
//获得请求发送的端口
public int getServerPort();
/**
* Retrieves the body of the request as character data using
* a <code>BufferedReader</code>. The reader translates the character
* data according to the character encoding used on the body.
* Either this method or {@link #getInputStream} may be called to read the body, not both.
* @return a <code>BufferedReader</code> containing the body of the request
* @exception UnsupportedEncodingException if the character set encoding used is not supported and the
* text cannot be decoded
* @exception IllegalStateException if {@link #getInputStream} method has been called on this request
* @exception IOException if an input or output exception occurred
* @see #getInputStream
*/
//检索请求body数据作为字符数据使用bufferedReader
public BufferedReader getReader() throws IOException;
/**
* Returns the Internet Protocol (IP) address of the client
* or last proxy that sent the request.
* For HTTP servlets, same as the value of the
* CGI variable <code>REMOTE_ADDR</code>.
* @return a <code>String</code> containing the
* IP address of the client that sent the request
*/
//获得客户端或最后一次代理的IP地址
public String getRemoteAddr();
/**
* Returns the fully qualified name of the client
* or the last proxy that sent the request.
* If the engine cannot or chooses not to resolve the hostname
* (to improve performance), this method returns the dotted-string form of
* the IP address. For HTTP servlets, same as the value of the CGI variable
* <code>REMOTE_HOST</code>.
* @return a <code>String</code> containing the fully
* qualified name of the client
*/
//获得发送请求的主机名或最后一次代理的主机名
public String getRemoteHost();
/**
* Stores an attribute in this request.
* Attributes are reset between requests. This method is most
* often used in conjunction with {@link RequestDispatcher}.
* <p>Attribute names should follow the same conventions as
* package names. Names beginning with <code>java.*</code>,
* <code>javax.*</code>, and <code>com.sun.*</code>, are
* reserved for use by Sun Microsystems.
*<br> If the object passed in is null, the effect is the same as
* calling {@link #removeAttribute}.
* <br> It is warned that when the request is dispatched from the
* servlet resides in a different web application by
* <code>RequestDispatcher</code>, the object set by this method
* may not be correctly retrieved in the caller servlet.
* @param name a <code>String</code> specifying
* the name of the attribute
* @param o the <code>Object</code> to be stored
*/
//在请求中设置一个属性
public void setAttribute(String name, Object o);
/**
*
* Removes an attribute from this request. This method is not
* generally needed as attributes only persist as long as the request
* is being handled.
*
* <p>Attribute names should follow the same conventions as
* package names. Names beginning with <code>java.*</code>,
* <code>javax.*</code>, and <code>com.sun.*</code>, are
* reserved for use by Sun Microsystems.
* @param name a <code>String</code> specifying
* the name of the attribute to remove
*/
//删除一个请求中的一个属性name
public void removeAttribute(String name);
/**
* Returns the preferred <code>Locale</code> that the client will
* accept content in, based on the Accept-Language header.
* If the client request doesn't provide an Accept-Language header,
* this method returns the default locale for the server.
* @return the preferred <code>Locale</code> for the client
*/
//
public Locale getLocale();
/**
* Returns an <code>Enumeration</code> of <code>Locale</code> objects
* indicating, in decreasing order starting with the preferred locale, the
* locales that are acceptable to the client based on the Accept-Language header.
* If the client request doesn't provide an Accept-Language header,
* this method returns an <code>Enumeration</code> containing one
* <code>Locale</code>, the default locale for the server.
* @return an <code>Enumeration</code> of preferred <code>Locale</code> objects for the client
*/
public Enumeration getLocales();
/**
*
* Returns a boolean indicating whether this request was made using a
* secure channel, such as HTTPS.
* @return a boolean indicating if the request was made using a
* secure channel
*/
//是否使用的安全性的通道
public boolean isSecure();
/**
* Returns a {@link RequestDispatcher} object that acts as a wrapper for
* the resource located at the given path.
* A <code>RequestDispatcher</code> object can be used to forward
* a request to the resource or to include the resource in a response.
* The resource can be dynamic or static.
* <p>The pathname specified may be relative, although it cannot extend
* outside the current servlet context. If the path begins with
* a "/" it is interpreted as relative to the current context root.
* This method returns <code>null</code> if the servlet container
* cannot return a <code>RequestDispatcher</code>.
* <p>The difference between this method and {@link
* ServletContext#getRequestDispatcher} is that this method can take a
* relative path.
* @param path a <code>String</code> specifying the pathname
* to the resource. If it is relative, it must be
* relative against the current servlet.
* @return a <code>RequestDispatcher</code> object
* that acts as a wrapper for the resource
* at the specified path, or <code>null</code>
* if the servlet container cannot return a
* <code>RequestDispatcher</code>
* @see RequestDispatcher
* @see ServletContext#getRequestDispatcher
*/
//
public RequestDispatcher getRequestDispatcher(String path);
/**
*
* @deprecated As of Version 2.1 of the Java Servlet API,
* use {@link ServletContext#getRealPath} instead.
*
*/
public String getRealPath(String path);
/**
* Returns the Internet Protocol (IP) source port of the client
* or last proxy that sent the request.
*
* @return an integer specifying the port number
*
* @since 2.4
*/
//获得IP端口
public int getRemotePort();
/**
* Returns the host name of the Internet Protocol (IP) interface on
* which the request was received.
* @return a <code>String</code> containing the host
* name of the IP on which the request was received.
* @since 2.4
*/
//获得请求的主机名
public String getLocalName();
/**
* Returns the Internet Protocol (IP) address of the interface on
* which the request was received.
* @return a <code>String</code> containing the
* IP address on which the request was received.
* @since 2.4
*/
//获取请求的服务的IP地址
public String getLocalAddr();
/**
* Returns the Internet Protocol (IP) port number of the interface
* on which the request was received.
* @return an integer specifying the port number
* @since 2.4
*/
//端口
public int getLocalPort();
}