SpringMVC----Jackson运用

本文演示了如何使用SpringMVC框架中的ResponseBody注解,配合Jackson库将Java Map对象和List<Map>对象转换为JSON字符串的过程。通过具体的代码示例,展示了如何设置pom.xml依赖,以及如何在控制器中实现JSON数据的映射。

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1.pom.xml

     <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.8.5</version>
        </dependency>

2.测试代码

@RequestMapping("/doMapJsonString")
    @ResponseBody
    public Map<String,Object> doMapJsonString(){
        Map<String, Object> map = new LinkedHashMap<>();
        map.put("id", 100);
        map.put("name", "BeiJing");
        return map;
        //系统底层会基于返回值查找对应的转换,将对象转换为指定格式的字符串
    }
    
    @RequestMapping("/doMapJsonString02")
    @ResponseBody
    public List<Map<String,Object>> doMapJsonString02(){
        List<Map<String,Object>> list = new ArrayList<>();
        Map<String, Object> map = new LinkedHashMap<>();
        map.put("id", 100);
        map.put("name", "BeiJing");
        list.add(map);
        map = new LinkedHashMap<>();
        map.put("id", 200);
        map.put("name", "ShangHai");
        list.add(map);
        return list;
        //系统底层会基于返回值查找对应的转换,将对象转换为指定格式的字符串
    }

3.结果

[{"id":100,"name":"BeiJing"},{"id":200,"name":"ShangHai"}]

 

转载于:https://www.cnblogs.com/yikuan-919/p/9739869.html

### 项目结构和配置 为了构建一个基于 `spring-context`, `spring-tx`, `spring-jdbc`, `spring-webmvc`, `mybatis`, `pagehelper`, `mybatis-spring`, `java.servlet-api`, `mysql-connector-java`, `druid`, `fastjson`, `jackson-core`, `jackson-databind`, `jackson-annotations` 和 `tomcat7-maven-plugin` 的 Maven 项目,以下是详细的步骤说明。 #### 1. 创建 Maven 项目的 POM 文件 POM 文件定义了项目的依赖关系以及插件配置。以下是一个完整的 POM 配置示例: ```xml <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.example</groupId> <artifactId>maven-project-demo</artifactId> <version>1.0-SNAPSHOT</version> <packaging>war</packaging> <properties> <spring.version>5.3.9</spring.version> <mybatis.version>3.5.7</mybatis.version> <pagehelper.version>1.4.1</pagehelper.version> <mysql.connector.java.version>8.0.26</mysql.connector.java.version> <druid.version>1.2.8</druid.version> <fastjson.version>1.2.78</fastjson.version> <jackson.version>2.12.3</jackson.version> <servlet.api.version>4.0.1</servlet.api.version> <tomcat.plugin.version>2.2</tomcat.plugin.version> </properties> <dependencies> <!-- Spring Framework --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-tx</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jdbc</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring.version}</version> </dependency> <!-- MyBatis and PageHelper --> <dependency> <groupId>org.mybatis.spring</groupId> <artifactId>mybatis-spring</artifactId> <version>2.0.6</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>${mybatis.version}</version> </dependency> <dependency> <groupId>com.github.pagehelper</groupId> <artifactId>pagehelper-spring-boot-starter</artifactId> <version>${pagehelper.version}</version> </dependency> <!-- Database Connection --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>${mysql.connector.java.version}</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>${druid.version}</version> </dependency> <!-- JSON Processing --> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>${fastjson.version}</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>${jackson.version}</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>${jackson.version}</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>${jackson.version}</version> </dependency> <!-- Servlet API --> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>${servlet.api.version}</version> <scope>provided</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <version>${tomcat.plugin.version}</version> <configuration> <path>/demo</path> </configuration> </plugin> </plugins> </build> </project> ``` 此部分提供了所有必要的依赖项及其版本号[^1]。 #### 2. 配置核心 XML 文件 ##### (a) spring.xml 用于加载全局 Bean 定义和其他基础配置。 ```xml <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <!-- 数据源配置 --> <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close"> <property name="url" value="${jdbc.url}" /> <property name="username" value="${jdbc.username}" /> <property name="password" value="${jdbc.password}" /> <property name="driverClassName" value="${jdbc.driverClassName}" /> </bean> <!-- SqlSessionFactoryBean 配置 --> <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource"/> <property name="mapperLocations" value="classpath*:mappers/*.xml"/> </bean> <!-- Mapper 扫描器 --> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="basePackage" value="com.example.mapper"/> </bean> </beans> ``` ##### (b) spring-mvc.xml 用于 Web 层的 MVC 配置。 ```xml <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <!-- 开启注解扫描 --> <context:component-scan base-package="com.example.controller"/> <!-- 启用MVC特性 --> <mvc:annotation-driven/> <!-- 视图解析器 --> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/views/" /> <property name="suffix" value=".jsp" /> </bean> </beans> ``` ##### (c) mybatis-config.xml MyBatis 的全局配置文件。 ```xml <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration> <settings> <setting name="cacheEnabled" value="true"/> <setting name="lazyLoadingEnabled" value="false"/> </settings> </configuration> ``` #### 3. JDBC 配置属性文件 (`jdbc.properties`) 提供数据库连接参数。 ```properties jdbc.driverClassName=com.mysql.cj.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/demo_db?useSSL=false&serverTimezone=UTC jdbc.username=root jdbc.password=password ``` --- ### 总结 上述内容涵盖了如何通过 Maven 构建并配置 SSM(Spring + SpringMVC + MyBatis)框架所需的全部组件,并引入了额外工具如 Druid 连接池、PageHelper 分页插件以及 Jackson/FastJSON 序列化支持[^2][^3].
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