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If you need to jump out of a new window or page , So you need to be in WEB-INF New China jsp file , Corresponding to the new interface / window , And then in controller Add a method to the layer , Use requestMapping annotation , Forward to the corresponding page

If you want to return to a page , that controller Layer does not need requestBody annotation

Concrete realization
json

Use ajex, General interface return data will be encapsulated as JSON Format

JSON Often used with XML compare , because JSON In fact, the birth of the new century has to be replaced more or less XNL It means . comparison XML,JSON The advantages are as follows :

No end tag , Shorter length , Read and write faster
Can be directly JavaScript Interpreter parsing
You can use arrays

Ajex What is it? ？
(70 Bar message ) Just read this one ！-Ajax Detailed explanation _ A fish sleeping with a cat _ The blog of -CSDN Blog

It is used when the front and back ends need to transfer data

Merge tables

select *
from student as s inner join banji as b
on s.banji_id=b.id;

Interceptor

Two new packages ：config Under bag WebConfigurer.java and Interceptor Under bag LoginInterceptor.java

Rights management

Use... In the interface display if Judge

If in index.jsp in , Do not want non administrators to see the user management bar , So only user.typ==0 This column is displayed only when , Otherwise it doesn't show

<c:if test="${user.type==0}">
                            <dd>
                                <a href="javascript:;"
                                   data-url="/user/getUserListPage"
                                   class="site-demo-active"> user </a>
                            </dd>

                        </c:if>

Plaintext encryption

Import in the project MD5util.java Tool class

stay UserServiceImpl in

public void add(User user) {
//         Set plaintext encryption for passwords 
        user.setPassword(MD5Util.MD5Encode(user.getPassword()));
        userMapper.add(user);
    }

When adding a new user , The password entered will be automatically encrypted and saved in the database

How to compare the password entered during login with the password encrypted in the database ？

The password for login is also encrypted

stay UserServiceImpl in

@Override
    public User login(String name, String password) {
        return userMapper.login(name,MD5Util.MD5Encode(password));
    }

After setting clear text login , The user's password becomes an encrypted unordered string state

If you want to add users in the background database , You need to put the password you want to enter in MD5 Encrypt in the website , And save it in the database

Add salt

public void add(User user) {
//         When adding users , Set plaintext encryption for passwords 
//         Add “ salt ”, Add a string after the encrypted string , It can make the encryption more efficient 
        user.setPassword(MD5Util.MD5Encode(user.getPassword()+MD5Util.salt));
        userMapper.add(user);
    }

Salt value on MD5Util In the tool class

public class MD5Util {

//     Salt value , Strengthen the encryption of passwords 
    public static String salt = "sdut*55//66";
……
}

Add class options when adding students

1. studentController Medium getStudentAddPage Method , You need to get a list of all the class names list, So use model Open up memory to save all class names obtained from the background

@RequestMapping("/getStudentAddPage")
    public String getStudentAddPage(Model model){
        List<Banji> banjiList=banjiService.selectAll();
        model.addAttribute("banjiList",banjiList);
        return "/WEB-INF/student_add.jsp";
    }

2. Student Classes should be added to entity classes id Properties of ：banjiId

3. stay student.add Add a drop-down box to the div label , Just existed model The class name in the memory can be used for Loop it out

value On behalf of the class id Value

<%--  When adding a student, select the student class from the drop-down box  --%>
        <div class="layui-form-item">
            <label class="layui-form-label"> class </label>
            <div class="layui-input-block">
        <%--    banjiId:1 --%>
                <select name="banjiId">
                    <option>-- Please select ---</option>
<%--                     Use for Loop to show all the class names --%>
                    <c:forEach items="${banjiList}" var="banji">
                        <option value=${banji.id}>${banji.name}</option>
                    </c:forEach>
                </select>
            </div>
        </div>

4. When adding students, you need to put the students' classes id And add it , So we need to change studentMapper.xml Medium add Method , Add a... To the data sheet banji_id,value To add a banjiId Properties of

<!--void add(Student student);-->
    <insert id="add" parameterType="Student">
        insert into student(name,age,gender,banji_id) values(#{name},#{age},#{gender},#{banjiId})
    </insert>

League table query

1. I want to display the student information and the class name in the student list display page . Because the class is saved in the student table id, class id The corresponding class name needs to be found in the class table , So search sql Statement needs to use inner join key word .

<select id="selectByPage" resultType="StudentVo">
--  League table query 
        select s.id,s.name,s.age,s.gender,s.banji_id,b.name as banjiName
        from student as s inner join banji as b
        <where>
            <if test="student.id!=null">
                and id=#{student.id}
            </if>

     <!--like Fuzzy search  concat：-->
            <if test="student.name!=null and student.name!=''">
                and name like concat('%',#{student.name},'%')
            </if>
        </where>

        limit #{offset},#{limit}
    </select>

2. You need to create a new entity class named StudentVo, Used to save students' id, full name , Gender , Age and class name

package com.sdut.springboot.entity;

import lombok.Data;

@Data
public class StudentVo {
    private Integer age;
    private String gender;
    private String name;
    private Integer id;
    private String banjiName;
}

3. hold controller layer 、service layer 、mapper The return value of the corresponding paging method in the layer is from Student Class to StudentVo class

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