springMVC 400 错误总结

旧城等待， 2022-07-11 11:19 132阅读 0赞

## 1.参数名称本身对不上的情况 ##

后台接受参数名称为 a，前台传递参数为 b，当然你的情况不会差别这么打，你可能只是某个字母弄错了，比如 前台传递为 word，后台接受为 wrod。

## 2.多传递了参数 ##

比如我们向后台传递一个实体对象参数：这个对象里面有只有2个参数 id、name，而你传递的参数里面多加了一个 age，这种也是会报错的。

package com.fafree.entity.query;
    
    import java.io.Serializable;
    
    public class UserQuery implements Serializable { 
        private static final long serialVersionUID = 1L;
        private int id;
        private String name;
    
        public int getId() {
            return id;
        }
    
        public void setId(int id) {
            this.id = id;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
    }

## 3.@RequestBody 接受对象里面,如果已经有了非空构造函数，那么它同时必须要有默认的空构造函数，注意这个构造函数一定要为空 ##

## 4.一个包含了@RequestBody 和 @RequestParam 绑定的 ajax 例子： ##

1.  @RequestBody 对应的实体
    
        package com.fafree.entity.query;
        
        import java.io.Serializable;
        
        // 如果已经有了带参数的构造函数，那么必须添加无参数的构造函数
        public class SysUserQuery implements Serializable { 
        
            public SysUserQuery() {
                super();
            }
        // 有参数的构造函数
            public SysUserQuery(Long id, Long organizationId, String username, String password, String salt, String roleIds,
                    Boolean locked) {
                super();
                this.id = id;
                this.organizationId = organizationId;
                this.username = username;
                this.password = password;
                this.salt = salt;
                this.roleIds = roleIds;
                this.locked = locked;
            }
        
            /** * 主键 -> id */
            private Long id;
        
            /** * 组织 id -> organization_id */
            private Long organizationId;
        
            /** * 用户名称 -> username */
            private String username;
        
            /** * 密码 -> password */
            private String password;
        
            /** * 盐 -> salt */
            private String salt;
        
            /** * 角色 id -> role_ids */
            private String roleIds;
        
            /** * 是否锁定：0否，1是 -> locked */
            private Boolean locked;
        
            /** * This field was generated by MyBatis Generator. * This field corresponds to the database table sys_user * * @mbggenerated */
            private static final long serialVersionUID = 1L;
        
            public String getCredentialsSalt() {
                return username + salt;
            }
        
            public Long getId() {
                return id;
            }
        
            public void setId(Long id) {
                this.id = id;
            }
        
            public Long getOrganizationId() {
                return organizationId;
            }
        
            public void setOrganizationId(Long organizationId) {
                this.organizationId = organizationId;
            }
        
            public String getUsername() {
                return username;
            }
        
            public void setUsername(String username) {
                this.username = username == null ? null : username.trim();
            }
        
            public String getPassword() {
                return password;
            }
        
            public void setPassword(String password) {
                this.password = password == null ? null : password.trim();
            }
        
            public String getSalt() {
                return salt;
            }
        
            public void setSalt(String salt) {
                this.salt = salt == null ? null : salt.trim();
            }
        
            public String getRoleIds() {
                return roleIds;
            }
        
            public void setRoleIds(String roleIds) {
                this.roleIds = roleIds == null ? null : roleIds.trim();
            }
        
            public Boolean getLocked() {
                return locked;
            }
        
            public void setLocked(Boolean locked) {
                this.locked = locked;
            }
        
            @Override
            public String toString() {
                return "SysUser {"
                        + "id=" + id + ","
                        + "organizationId=" + organizationId + ","
                        + "username=" + username+ ","
                        + "password=" + password + ","
                        + "salt=" + salt + ","
                        + "roleIds=" + roleIds + ","
                        + "locked=" + locked
                        + "}";
            }
        }
2.  ajax请求
    
        function loadData(pageNum, pageSize) { 
             // 设置请求的 url
             var url = "${ctx}/user/list-content?pageNum=" + pageNum + "&pageSize=" + pageSize;
            $.ajax({
                url:url,
                type:'POST',
                contentType: "application/json; charset=utf-8",
                // 请求参数可以比对象里面的少，但是不能多
                data:JSON.stringify({username:"dada"}),
                dataType:'html',
                async:true,
                success: function(result){ 
                    $("#list_content_div").empty();
                    $("#list_content_div").append(result);
                },error:function(){ 
                    alert("error");
                }
            });
        }
3.  后台接受方法
    
        @RequestMapping(value="/list-content", method = {RequestMethod.POST, RequestMethod.GET})
            public String listContent(Model model, @RequestBody SysUserQuery query,
                    @RequestParam(value = "pageNum", defaultValue = "1")Integer pageNum,
                    @RequestParam(value = "pageSize", defaultValue = "10")Integer pageSize) {
                PageParam pp = new PageParam();
                pp.setPageNum(pageNum);
                pp.setPageSize(pageSize);
                PageInfo<SysUser> pageInfo =  userService.findAllByPage(pp);
                model.addAttribute("pageInfo", pageInfo);
                return "user/list-content";
            }