帮我写一段java代码 向我后台进行用户名称查询张三，get请求，然后后台模拟数据库取出值并返回查询的值，帮我写一下完成的代码

当然可以，这是一个简单的Java代码示例，使用了HTTP客户端库如Apache HttpClient来进行GET请求。在这个例子中，我们假设你已经有一个Rest API接口`http://example.com/api/user`用于接收查询请求。请注意，这只是一个基本的框架，实际应用可能需要连接到真实的数据库进行查询。

import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

public class UserSearch {
    private static final String USER_NAME = "张三";
    private static final String API_URL = "http://example.com/api/user";

    public static void main(String[] args) throws Exception {
        // 创建HttpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();

        try {
            // 构造HttpGet请求
            HttpGet request = new HttpGet(API_URL + "?name=" + USER_NAME);

            // 发送请求
            System.out.println("Sending GET request to " + API_URL);
            CloseableHttpResponse response = httpClient.execute(request);

            try {
                // 检查请求是否成功
                if (response.getStatusLine().getStatusCode() == 200) {
                    // 获取响应体
                    HttpEntity entity = response.getEntity();
                    String responseBody = EntityUtils.toString(entity, "UTF-8");

                    // 输出查询结果
                    System.out.println("Query result for user '张三':");
                    System.out.println(responseBody);
                } else {
                    System.err.println("Failed with status code: " + response.getStatusLine());
                }
            } finally {
                // 关闭响应体
                response.close();
            }
        } finally {
            // 关闭HttpClient
            httpClient.close();
        }
    }
}