使用GSON库。以下是示例代码

Use GSON library for that. Here is the sample code

List<String> foo = new ArrayList<String>();
foo.add("A");
foo.add("B");
foo.add("C");

String json = new Gson().toJson(foo );

这是Gson的maven依赖

Here is the maven dependency for Gson

<dependencies>
    <!--  Gson: Java to Json conversion -->
    <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>2.2.2</version>
        <scope>compile</scope>
    </dependency>
</dependencies>

或者你可以直接从这里下载jar并把它放在你的班级路径中

Or you can directly download jar from here and put it in your class path

http://code.google.com/p/google-gson/downloads/detail?name=gson-1.0.jar&can=4&q=

要将Json发送到客户端，您可以使用spring或简单的servlet添加此代码

To send Json to client you can use spring or in simple servlet add this code

response.getWriter（）。write（json ）;

response.getWriter().write(json);