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This article shows you how to solve the front-end data processing and garbled problems of Java, the content is concise and easy to understand, it can definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

First, data processing 1. Processing submitted data

1. The submitted name is the same as the parameter name of the method

/ localhost:8080/user/t1?name=xxx;@GetMapping ("/ T1") public String test1 (String name, Model model) {/ / 1. Receive the front-end parameter System.out.println ("the received front-end parameter is:" + name); / / 2. Pass the returned result to the front-end model.addAttribute ("msg", name); / / 3. Jump to view return "test";}

two。 The submitted name does not match the parameter name of the method

/ / add @ RequestParam ("username") to know that the localhost:8080/user/t1?username=xxx; is received from the front end. At this point, @ GetMapping ("/ T1") public String test1 (@ RequestParam ("username") String name, Model model) {/ / 1 must be identified by username. Receive the front-end parameter System.out.println ("the received front-end parameter is:" + name); / / 2. Pass the returned result to the front-end model.addAttribute ("msg", name); / / 3. Jump to view return "test";}

3. Submit an object

/ / the front end receives an object: id, name, age//localhost:8080/user/t1?id=1&name=xxx&age=2;/** 1. Receive the parameters passed by the front-end user, determine the name of the parameter, and assume that the name can be used directly in the method. Suppose you are passing an object User that matches the field name in the User object: ok if the name is the same. Otherwise, it will not match * * / @ GetMapping ("/ T2") public String test2 (User user) {System.out.println (user); / / 3. Jump to view return "test";}

Using an object, the parameter name passed by the front end must be the same as the object name, otherwise it is empty.

two。 The data is displayed to the front end

2.1 ModelAndView

Public ModelAndView handleRequest (HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {ModelAndView modelAndView = new ModelAndView (); modelAndView.addObject ("msg", "ControllerTest1"); modelAndView.setViewName ("test"); return modelAndView;}

2.2 Model

@ RequestMapping ("/ T2") public String test (Model model) {model.addAttribute ("msg", "ControllerTest2"); return "test";}

2.3 ModelMap

@ GetMapping ("/ T3") public String test3 (@ RequestParam ("username") String name,Model map) {map.addAttribute ("name", name); return "test";}

Contrast:

While storing the data, ModelAndView can set the returned logical view to control the jump of the display layer.

ModelMap inherits LinkedHashMap and not only implements some of its own methods, but also inherits the methods and features of LinkedHashMap

A few methods of Model are suitable for storing data, which simplifies the novice's operation and understanding of Model objects; in most cases, Model is used directly.

2. Garbled code problem

1.form form

Title

two。 Write a controller

@ Controllerpublic class EncodingController {@ PostMapping ("/ encoding/t1") public String test (String name, Model model) {model.addAttribute ("msg", name); return "test";}}

3. Test result

It was all right in front of me, and it turned out to be this.

Solution:

Check to see if the UTF-8 is set in your Tomcat. Under your own download path-conf-server.xml

1) modify the submission method

Change the submission mode post method to get method

2) Spring provides filters that can be configured directly in web.xml. (this is basically enough.)

Encoding org.springframework.web.filter.CharacterEncodingFilter encoding utf-8 encoding / *

3) filter solution (this is not good, the function is not complete)

Package com.hxl.filter;import javax.servlet.*;import java.io.IOException;public class EncodingFilter implements Filter {@ Override public void init (FilterConfig filterConfig) throws ServletException {} @ Override public void doFilter (ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {servletRequest.setCharacterEncoding ("utf-8"); servletResponse.setCharacterEncoding ("utf-8"); filterChain.doFilter (servletRequest,servletResponse);} @ Override public void destroy () {}}

Register after you finish writing (web.xml).

Encoding com.hxl.filter.EncodingFilter encoding /

4) Divine Custom filter

Package com.hxl.filter;import javax.servlet.*;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.io.UnsupportedEncodingException;import java.util.Map / * filter for solving all garbled codes in get and post requests * / public class EncodingFilter implements Filter {@ Override public void destroy () {} @ Override public void doFilter (ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {/ / handles response character encoding HttpServletResponse myResponse= (HttpServletResponse) response; myResponse.setContentType ("text/html;charset=UTF-8") / / transformed to a protocol-related object HttpServletRequest httpServletRequest = (HttpServletRequest) request; / / A pair of request wrapper enhancements HttpServletRequest myrequest = new MyRequest (httpServletRequest); chain.doFilter (myrequest, response);} @ Override public void init (FilterConfig filterConfig) throws ServletException {}} / / Custom request object, HttpServletRequest wrapper class class MyRequest extends HttpServletRequestWrapper {private HttpServletRequest request; / / tag private boolean hasEncode whether encoded or not / / define a constructor that can be passed in a HttpServletRequest object to decorate it with public MyRequest (HttpServletRequest request) {super (request); / / super must write this.request = request;} / / A pair of enhanced methods to override @ Override public Map getParameterMap () {/ / get the request method String method = request.getMethod () first If (method.equalsIgnoreCase ("post")) {/ / post request try {/ / handle post garbled request.setCharacterEncoding ("utf-8"); return request.getParameterMap ();} catch (UnsupportedEncodingException e) {e.printStackTrace () }} else if (method.equalsIgnoreCase ("get")) {/ / get request Map parameterMap = request.getParameterMap (); if (! hasEncode) {/ / ensure that the get manual coding logic runs for (String parameterName: parameterMap.keySet ()) {String [] values = parameterMap.get (parameterName) only once If (values! = null) {for (int I = 0; I < values.length) Try {/ / handle get garbled values [I] = new String (values [I] .getBytes ("ISO-8859-1"), "utf-8") } catch (UnsupportedEncodingException e) {e.printStackTrace ();}} hasEncode = true;} return parameterMap } return super.getParameterMap ();} / / take a value @ Override public String getParameter (String name) {Map parameterMap = getParameterMap (); String [] values = parameterMap.get (name); if (values = = null) {return null;} return values [0] / / retrieve the first value of the parameter} / / take all values @ Override public String [] getParameterValues (String name) {Map parameterMap = getParameterMap (); String [] values = parameterMap.get (name); return values;}}

It also needs to be configured in web.xml

The above content is how to solve the front-end data processing and garbled problems of Java. Have you learned the knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

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