5.22

政策查询系统
• 所花时间：4
• 代码行数：324
• 博客容量：1
• 代码如下：

package utils;

import utils.Policy;

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class PolicyDAO {
    private final static String driver = "com.mysql.jdbc.Driver";
    private static String url="jdbc:mysql://localhost:3306/party?useUnicode=true&characterEncoding=UTF-8";
    private static String user="root";
    private static String password="1234";
    public static List<Policy> queryByPage(int currentPage, int pageSize) {
        Connection conn = getCon();
        List<Policy> ls = new ArrayList<>();
        String sql = "SELECT * FROM policy LIMIT ?, ?";
        int offset = (currentPage - 1) * pageSize;

        try {
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setInt(1, offset);
            ps.setInt(2, pageSize);
            ResultSet rs = ps.executeQuery();
            while (rs.next()) {
                Policy policy = new Policy();
                policy.id = rs.getString(1);
                policy.category = rs.getString(4);
                policy.document = rs.getString(6);
                policy.form = rs.getString(7);
                policy.name = rs.getString(2);
                policy.organ = rs.getString(8);
                policy.perdata = rs.getDate(11).toString();
                policy.pubdata = rs.getDate(10).toString();
                policy.range = rs.getString(5);
                policy.viadata = rs.getDate(9).toString();
                policy.text = rs.getString(19);
                policy.type = rs.getString(3);
                ls.add(policy);
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            try {
                conn.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
        return ls;
    }

    public static Connection getCon(){
        Connection connection=null;
        try {
            Class.forName(driver);
            connection=DriverManager.getConnection(url,user,password);
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return connection;
    }
    public static List<Policy> queryAll(){
        Connection conn=getCon();
        List<Policy> ls=new ArrayList<>();
        String sql="select * from policy";
        try {
            PreparedStatement ps=conn.prepareStatement(sql);
            ResultSet rs=ps.executeQuery();
            while (rs.next()){
                Policy policy=new Policy();
                policy.id=rs.getString("id");
                policy.category=rs.getString("category");
                policy.document=rs.getString("document");
                policy.form=rs.getString("form");
                policy.name=rs.getString("name");
                policy.organ=rs.getString("organ");
                policy.perdata = rs.getDate(11).toString();
                policy.pubdata = rs.getDate(10).toString();
                policy.range=rs.getString("range");
                policy.viadata = rs.getDate(9).toString();
                policy.text=rs.getString("text");
                policy.type=rs.getString("type");
                ls.add(policy);
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return ls;
    }
    public static List<Policy> searchPolicies(String policyName, String documentNumber, String publishingOrgan) {
        Connection conn = getCon();
        List<Policy> policies = new ArrayList<>();
        String sql = "SELECT * FROM policy WHERE name LIKE ? AND document LIKE ? AND organ LIKE ?";

        try {
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setString(1, "%" + policyName + "%");
            ps.setString(2, "%" + documentNumber + "%");
            ps.setString(3, "%" + publishingOrgan + "%");
            ResultSet rs = ps.executeQuery();

            while (rs.next()) {
                Policy policy = new Policy();
                policy.name = rs.getString("name");
                policy.document = rs.getString("document");
                policy.organ = rs.getString("organ");
                policy.pubdata = rs.getString("pubdata");
                policy.category = rs.getString("category");
                policies.add(policy);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return policies;
    }
    public static Policy getPolicyById(int policyId) {
        Connection conn = getCon();
        String sql = "SELECT * FROM policy WHERE id = ?";
        Policy policy = null;

        try {
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setInt(1, policyId);
            ResultSet rs = ps.executeQuery();

            if (rs.next()) {
                policy = new Policy();
                policy.id = rs.getString("id");
                policy.category = rs.getString("category");
                policy.document = rs.getString("document");
                policy.form = rs.getString("form");
                policy.name = rs.getString("name");
                policy.organ = rs.getString("organ");
                policy.perdata = rs.getDate("perdata").toString();
                policy.pubdata = rs.getDate("pubdata").toString();
                policy.range = rs.getString("range");
                policy.viadata = rs.getDate("viadata").toString();
                policy.text = rs.getString("text");
                policy.type = rs.getString("type");
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            try {
                conn.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
        return policy;
    }
}
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

import com.google.gson.Gson;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import utils.Policy;
import utils.PolicyDAO;

@WebServlet(name = "searchPolicies", value = "/searchPolicies")
public class SearchPoliciesServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        // 获取查询条件
        String policyName = request.getParameter("policyName");
        String documentNumber = request.getParameter("documentNumber");
        String publishingOrgan = request.getParameter("publishingOrgan");

        // 标记是否有任何一个搜索框输入了内容
        boolean anyFieldEntered = false;
        if (policyName != null && !policyName.isEmpty()) {
            anyFieldEntered = true;
        } else if (documentNumber != null && !documentNumber.isEmpty()) {
            anyFieldEntered = true;
        } else if (publishingOrgan != null && !publishingOrgan.isEmpty()) {
            anyFieldEntered = true;
        }

        // 如果有任何一个搜索框输入了内容，则执行查询
        if (anyFieldEntered) {
            // 调用 DAO 层的方法查询数据
            List<Policy> matchedPolicies = new ArrayList<>();
            List<Policy> allPolicies = PolicyDAO.queryAll();

            for (Policy policy : allPolicies) {
                // 检查政策是否匹配任何一个搜索框的内容
                if (policyName != null && !policyName.isEmpty() && policy.name.contains(policyName)) {
                    matchedPolicies.add(policy);
                } else if (documentNumber != null && !documentNumber.isEmpty() && policy.document.contains(documentNumber)) {
                    matchedPolicies.add(policy);
                } else if (publishingOrgan != null && !publishingOrgan.isEmpty() && policy.organ.contains(publishingOrgan)) {
                    matchedPolicies.add(policy);
                }
            }

            // 将查询结果转换为 JSON 格式
            Gson gson = new Gson();
            String jsonPolicies = gson.toJson(matchedPolicies);

            // 设置响应类型为 JSON
            response.setContentType("application/json");
            response.setCharacterEncoding("UTF-8");

            // 将 JSON 数据发送回客户端
            PrintWriter out = response.getWriter();
            out.print(jsonPolicies);
            out.flush();
        }
    }
}