热火 凯尔特人,痴情司伴奏,王邦
spring boot可以大大简化持久化任务，几乎不需要写sql语句，在之前章节“spring boot 构建框架”中我们新建了一个spring boot应用程序，本章在原有的工程中与数据库建立连接。
spring boot有两种方法与数据库建立连接，一种是使用jdbctemplate，另一种集成mybatis，下面分别为大家介绍一下如何集成和使用这两种方式。
1. 使用jdbctemplate
<dependency> <groupid>mysql</groupid> <artifactid>mysql-connector-java</artifactid> </dependency> <dependency> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-starter-jdbc</artifactid> </dependency>
在resource文件夹下添加application.properties配置文件并输入数据库参数，内容如下：
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/test spring.datasource.username=root spring.datasource.password=123456 spring.datasource.driver-class-name=com.mysql.jdbc.driver spring.datasource.max-idle=10 spring.datasource.max-wait=1000 spring.datasource.min-idle=5 spring.datasource.initial-size=5 server.port=8012 server.session.timeout=10 server.tomcat.uri-encoding=utf-8
新建controller类测试数据库连接，实例如下：
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package com.example.demo;
import java.util.iterator;
import java.util.list;
import java.util.map;
import java.util.map.entry;
import java.util.set;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.jdbc.core.jdbctemplate;
import org.springframework.web.bind.annotation.pathvariable;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.restcontroller;
@restcontroller
@requestmapping("/mydb")
public class dbcontroller {
@autowired
private jdbctemplate jdbctemplate;
@requestmapping("/getusers")
public list<map<string, object>> getdbtype(){
string sql = "select * from appuser";
list<map<string, object>> list = jdbctemplate.queryforlist(sql);
for (map<string, object> map : list) {
set<entry<string, object>> entries = map.entryset( );
if(entries != null) {
iterator<entry<string, object>> iterator = entries.iterator( );
while(iterator.hasnext( )) {
entry<string, object> entry =(entry<string, object>) iterator.next( );
object key = entry.getkey( );
object value = entry.getvalue();
system.out.println(key+":"+value);
}
}
}
return list;
}
@requestmapping("/user/{id}")
public map<string,object> getuser(@pathvariable string id){
map<string,object> map = null;
list<map<string, object>> list = getdbtype();
for (map<string, object> dbmap : list) {
set<string> set = dbmap.keyset();
for (string key : set) {
if(key.equals("id")){
if(dbmap.get(key).equals(id)){
map = dbmap;
}
}
}
}
if(map==null)
map = list.get(0);
return map;
}
}
运行app输入地址输出数据库数据。
2. 集成mybatis
添加mybatis依赖，在pom.xml文件中增加如下：
<dependency> <groupid>org.mybatis.spring.boot</groupid> <artifactid>mybatis-spring-boot-starter</artifactid> <version>1.0.0</version> </dependency>
在resource文件夹下添加application.properties配置文件并输入数据库参数，如下：
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/test spring.datasource.username=root spring.datasource.password=123456 spring.datasource.driver-class-name=com.mysql.jdbc.driver spring.datasource.max-idle=10 spring.datasource.max-wait=1000 spring.datasource.min-idle=5 spring.datasource.initial-size=5 server.port=8012 server.session.timeout=10 server.tomcat.uri-encoding=utf-8
依次添加mapper的接口类和xml文件，类分别如下：
appmessagemapper.java
package com.example.demo.mapper;
import java.util.list;
import com.example.demo.bean.appmessage;
public interface appmessagemapper {
int deletebyprimarykey(string id);
int insert(appmessage record);
int insertselective(appmessage record);
appmessage selectbyprimarykey(string id);
int updatebyprimarykeyselective(appmessage record);
int updatebyprimarykey(appmessage record);
list<appmessage> selectall();
list<appmessage> getmessbyid(string id);
}
appmessagemapper.xml
<?xml version="1.0" encoding="utf-8" ?>
<!doctype mapper public "-//mybatis.org//dtd mapper 3.0//en" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.example.demo.mapper.appmessagemapper" >
<resultmap id="baseresultmap" type="com.example.demo.bean.appmessage" >
<id column="id" property="id" jdbctype="varchar" />
<result column="message" property="message" jdbctype="varchar" />
<result column="senddate" property="senddate" jdbctype="timestamp" />
</resultmap>
<sql id="base_column_list" >
id, message, senddate
</sql>
<select id="selectbyprimarykey" resultmap="baseresultmap" parametertype="java.lang.string" >
select
<include refid="base_column_list" />
from appuser_message
where id = #{id,jdbctype=varchar}
</select>
<delete id="deletebyprimarykey" parametertype="java.lang.string" >
delete from appuser_message
where id = #{id,jdbctype=varchar}
</delete>
<insert id="insert" parametertype="com.example.demo.bean.appmessage" >
insert into appuser_message (id, message, senddate
)
values (#{id,jdbctype=varchar}, #{message,jdbctype=varchar}, #{senddate,jdbctype=timestamp}
)
</insert>
<insert id="insertselective" parametertype="com.example.demo.bean.appmessage" >
insert into appuser_message
<trim prefix="(" suffix=")" suffixoverrides="," >
<if test="id != null" >
id,
</if>
<if test="message != null" >
message,
</if>
<if test="senddate != null" >
senddate,
</if>
</trim>
<trim prefix="values (" suffix=")" suffixoverrides="," >
<if test="id != null" >
#{id,jdbctype=varchar},
</if>
<if test="message != null" >
#{message,jdbctype=varchar},
</if>
<if test="senddate != null" >
#{senddate,jdbctype=timestamp},
</if>
</trim>
</insert>
<update id="updatebyprimarykeyselective" parametertype="com.example.demo.bean.appmessage" >
update appuser_message
<set >
<if test="message != null" >
message = #{message,jdbctype=varchar},
</if>
<if test="senddate != null" >
senddate = #{senddate,jdbctype=timestamp},
</if>
</set>
where id = #{id,jdbctype=varchar}
</update>
<update id="updatebyprimarykey" parametertype="com.example.demo.bean.appmessage" >
update appuser_message
set message = #{message,jdbctype=varchar},
senddate = #{senddate,jdbctype=timestamp}
where id = #{id,jdbctype=varchar}
</update>
<select id="selectall" resultmap="baseresultmap">
select
id, message, senddate
from appuser_message
order by senddate asc
</select>
<select id="getmessbyid" resultmap="baseresultmap" parametertype="java.lang.string">
select
id, message, senddate
from
appuser_message
where id = #{id,jdbctype=varchar}
order by senddate asc
</select>
</mapper>
appmessage.java
package com.example.demo.bean;
import java.util.date;
public class appmessage {
private string id;
private string message;
private date senddate;
public string getid() {
return id;
}
public void setid(string id) {
this.id = id == null ? null : id.trim();
}
public string getmessage() {
return message;
}
public void setmessage(string message) {
this.message = message == null ? null : message.trim();
}
public date getsenddate() {
return senddate;
}
public void setsenddate(date senddate) {
this.senddate = senddate;
}
}
appmessageservice.java
package com.example.demo.service;
import java.util.arraylist;
import java.util.list;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.stereotype.service;
import com.example.demo.bean.appmessage;
import com.example.demo.mapper.appmessagemapper;
@service
public class appmessageservice {
@autowired
private appmessagemapper mapper;
public list<appmessage> getmessage(){
list<appmessage> list = new arraylist<appmessage>();
list.add(mapper.selectbyprimarykey("xtt"));
//list = mapper.selectall();
return list;
}
public list<appmessage> getallmessage(){
list<appmessage> list = new arraylist<appmessage>();
list = mapper.selectall();
return list;
}
public int addmessage(appmessage appmessage) {
return mapper.insert(appmessage);
}
public list<appmessage> getmessagebyid(string id) {
return mapper.getmessbyid(id);
}
public int delmessage(string id) {
return mapper.deletebyprimarykey(id);
}
}
appmessagecontroller.java
package com.example.demo.controller;
import java.util.list;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.web.bind.annotation.requestbody;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.requestmethod;
import org.springframework.web.bind.annotation.requestparam;
import org.springframework.web.bind.annotation.restcontroller;
import com.example.demo.bean.appmessage;
import com.example.demo.service.appmessageservice;
@restcontroller
@requestmapping("/appmessage")
public class appmessagecontroller {
@autowired
private appmessageservice service;
@requestmapping("/getthree")
public list<appmessage> getthreeformessage(){
list<appmessage> list = service.getmessage();
return list;
}
@requestmapping("/getall")
public list<appmessage> getallmessage(){
list<appmessage> list = service.getallmessage();
int num = list.size();
if(null!=list && num>3){
for (int i = 0; i < num-3; i++) {
list.remove(0);
}
}
return list;
}
@requestmapping("/getbyid")
public list<appmessage> getmessagebyid(@requestparam("id") string id){
list<appmessage> list = service.getmessagebyid(id);
int num = list.size();
if(null!=list && num>5){
for (int i = 0; i < num-5; i++) {
list.remove(0);
}
}
return list;
}
@requestmapping(value = "/add",method = requestmethod.post)
// 或者采用@postmapping("/add")方法，更加节省代码的编写量
public int addmessage(@requestbody appmessage appmessage){
return service.addmessage(appmessage);
}
@requestmapping(value="/delmessagebyid",method=requestmethod.post)
// 或者采用@postmapping("/delmessagebyid")方法，更加节省代码的编写量
public int delmessagebyid(@requestparam("id") string id){
return service.delmessage(id);
}
}
问题描述？
springboot扫描包提示找不到mapper的问题，异常信息：
consider defining a bean of type in your configuration
分析原因
spring boot项目的bean装配默认规则是根据application类所在的包位置从上往下扫描，“application类”是指spring boot项目入口类。如果application类所在的包为：com.yoodb.blog，则只会扫描com.yoodb.blog包及其所有子包，如果service或dao所在包不在com.yoodb.blog及其子包下，则不会被扫描。
解决方法
方式一：使用注解@componentscan(value=”com.yoodb.blog”)，其中，com.yoodb.blog为包路径。
方式二：将启动类application放在上一级包中，注意的是application启动类必须要保证在包的根目录下。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持移动技术网。
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