帮我写一个Javaweb mvc模糊查询和多条件查询的分页显示的完整代码

好的，这里是一个JavaWeb MVC模糊查询和多条件查询的分页显示的完整代码示例。

1. 创建数据库表

我们创建一个名为`person`的表，包含`id`,`name`,`age`,`email`四个字段。

CREATE TABLE person (
  id INT NOT NULL AUTO_INCREMENT,
  name VARCHAR(50) NOT NULL,
  age INT NOT NULL,
  email VARCHAR(50) NOT NULL,
  PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

2. 实现实体类

我们创建一个名为`Person`的实体类，对应`person`表的字段。

public class Person {
    private int id;
    private String name;
    private int age;
    private String email;
    
    // getter和setter方法省略
}

3. 实现DAO层接口

我们创建一个名为`PersonDao`的数据访问层接口，包含模糊查询和多条件查询两个方法。

public interface PersonDao {
    int countAll();
    List<Person> findByKeyword(String keyword, int offset, int limit);
    List<Person> findByCondition(String name, int age, String email, int offset, int limit);
}

4. 实现DAO层实现类

我们创建一个名为`PersonDaoImpl`的数据访问层实现类，实现`PersonDao`接口中的方法。

public class PersonDaoImpl implements PersonDao {
    private final Connection conn;

    public PersonDaoImpl(Connection conn) {
        this.conn = conn;
    }
    
    @Override
    public int countAll() {
        String sql = "SELECT COUNT(*) FROM person";
        try (PreparedStatement stmt = conn.prepareStatement(sql)) {
            try (ResultSet rs = stmt.executeQuery()) {
                if (rs.next()) {
                    return rs.getInt(1);
                } else {
                    return 0;
                }
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public List<Person> findByKeyword(String keyword, int offset, int limit) {
        String sql = "SELECT * FROM person WHERE name LIKE ? OR email LIKE ? LIMIT ?, ?";
        try (PreparedStatement stmt = conn.prepareStatement(sql)) {
            stmt.setString(1, "%" + keyword + "%");
            stmt.setString(2, "%" + keyword + "%");
            stmt.setInt(3, offset);
            stmt.setInt(4, limit);
            try (ResultSet rs = stmt.executeQuery()) {
                List<Person> list = new ArrayList<>();
                while (rs.next()) {
                    Person p = new Person();
                    p.setId(rs.getInt("id"));
                    p.setName(rs.getString("name"));
                    p.setAge(rs.getInt("age"));
                    p.setEmail(rs.getString("email"));
                    list.add(p);
                }
                return list;
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public List<Person> findByCondition(String name, int age, String email, int offset, int limit) {
        String sql = "SELECT * FROM person WHERE 1=1";
        List<Object> params = new ArrayList<>();
        if (name != null && !name.isEmpty()) {
            sql += " AND name LIKE ?";
            params.add("%" + name + "%");
        }
        if (age > 0) {
            sql += " AND age = ?";
            params.add(age);
        }
        if (email != null && !email.isEmpty()) {
            sql += " AND email LIKE ?";
            params.add("%" + email + "%");
        }
        sql += " LIMIT ?, ?";
        params.add(offset);
        params.add(limit);
        try (PreparedStatement stmt = conn.prepareStatement(sql)) {
            for (int i = 0; i < params.size(); i++) {
                stmt.setObject(i + 1, params.get(i));
            }
            try (ResultSet rs = stmt.executeQuery()) {
                List<Person> list = new ArrayList<>();
                while (rs.next()) {
                    Person p = new Person();
                    p.setId(rs.getInt("id"));
                    p.setName(rs.getString("name"));
                    p.setAge(rs.getInt("age"));
                    p.setEmail(rs.getString("email"));
                    list.add(p);
                }
                return list;
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }
}

5. 实现Service层接口

我们创建一个名为`PersonService`的服务层接口，包含模糊查询和多条件查询两个方法。

public interface PersonService {
    int countAll();
    List<Person> findByKeyword(String keyword, int page, int pageSize);
    List<Person> findByCondition(String name, int age, String email, int page, int pageSize);
}

6. 实现Service层实现类

我们创建一个名为`PersonServiceImpl`的服务层实现类，实现`PersonService`接口中的方法，并调用`PersonDao`接口中的方法。

public class PersonServiceImpl implements PersonService {
    private final PersonDao dao;

    public PersonServiceImpl(PersonDao dao) {
        this.dao = dao;
    }
    
    @Override
    public int countAll() {
        return dao.countAll();
    }

    @Override
    public List<Person> findByKeyword(String keyword, int page, int pageSize) {
        int offset = (page - 1) * pageSize;
        return dao.findByKeyword(keyword, offset, pageSize);
    }

    @Override
    public List<Person> findByCondition(String name, int age, String email, int page, int pageSize) {
        int offset = (page - 1) * pageSize;
        return dao.findByCondition(name, age, email, offset, pageSize);
    }
}

7. 实现Controller层

我们创建一个名为`PersonController`的控制层，实现模糊查询和多条件查询的接口，返回分页数据。

@WebServlet("/person")
public class PersonController extends HttpServlet {
    private static final long serialVersionUID = 1L;
    private final PersonService service = new PersonServiceImpl(new PersonDaoImpl(ConnectionUtil.getConnection()));

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setCharacterEncoding("UTF-8");
        String keyword = request.getParameter("keyword");
        String name = request.getParameter("name");
        String ageStr = request.getParameter("age");
        String email = request.getParameter("email");
        int page = Integer.parseInt(request.getParameter("page"));
        int pageSize = Integer.parseInt(request.getParameter("pageSize"));
        List<Person> list;
        int count;
        if (keyword != null && !keyword.isEmpty()) {
            list = service.findByKeyword(keyword, page, pageSize);
            count = service.countAll();
        } else {
            int age = ageStr != null && !ageStr.isEmpty() ? Integer.parseInt(ageStr) : 0;
            list = service.findByCondition(name, age, email, page, pageSize);
            count = name != null || age > 0 || email != null ? list.size() : service.countAll();
        }
        int pageCount = (int) Math.ceil(count * 1.0 / pageSize);
        request.setAttribute("list", list);
        request.setAttribute("count", count);
        request.setAttribute("pageCount", pageCount);
        request.setAttribute("page", page);
        request.setAttribute("pageSize", pageSize);
        request.getRequestDispatcher("/WEB-INF/views/person.jsp").forward(request, response);
    }
}

8. 实现前端页面

我们创建一个名为`person.jsp`的前端页面，包含分页显示的表格和查询表单。

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Person List</title>
    <style>
        table {
            border-collapse: collapse;
            width: 100%;
        }

        th, td {
            text-align: left;
            padding: 8px;
            border-bottom: 1px solid #ddd;
        }

        tr:hover {
            background-color: #f5f5f5;
        }

        form {
            display: inline-block;
        }

        label {
            display: inline-block;
            width: 60px;
            text-align: right;
        }

        input, select {
            width: 150px;
            margin-right: 20px;
        }

        .pagination {
            display: inline-block;
            margin: 20px 0;
        }

        .pagination a {
            color: black;
            float: left;
            padding: 8px 16px;
            text-decoration: none;
            transition: background-color .3s;
            border: 1px solid #ddd;
            margin: 0 4px;
        }

        .pagination a.active {
            background-color: dodgerblue;
            color: white;
            border: 1px solid dodgerblue;
        }

        .pagination a:hover:not(.active) {
            background-color: #ddd;
        }
    </style>
</head>
<body>
<h1>Person List</h1>
<form method="get" action="${pageContext.request.contextPath}/person">
    <label>Keyword:</label>
    <input type="text" name="keyword" value="${param.keyword}">
    <input type="submit" value="Search">
</form>
<form method="get" action="${pageContext.request.contextPath}/person">
    <label>Name:</label>
    <input type="text" name="name" value="${param.name}">
    <label>Age:</label>
    <input type="number" name="age" value="${param.age}">
    <label>Email:</label>
    <input type="text" name="email" value="${param.email}">
    <input type="submit" value="Search">
</form>
<table>
    <tr>
        <th>ID</th>
        <th>Name</th>
        <th>Age</th>
        <th>Email</th>
    </tr>
    <c:forEach var="p" items="${list}">
        <tr>
            <td>${p.id}</td>
            <td>${p.name}</td>
            <td>${p.age}</td>
            <td>${p.email}</td>
        </tr>
    </c:forEach>
</table>
<div class="pagination">
    <c:forEach var="i" begin="1" end="${pageCount}">
        <a href="${pageContext.request.contextPath}/person?page=${i}&pageSize=${pageSize}&keyword=${param.keyword}&name=${param.name}&age=${param.age}&email=${param.email}" class="${page==i?'active':''}">${i}</a>
    </c:forEach>
</div>
</body>
</html>

至此，我们就完成了JavaWeb MVC模糊查询和多条件查询的分页显示的完整代码示例。