首先jsp页面有一ul用于展现Tree

加载Tree

    	
     		
      			
       				
        treeNodes			
       		
      	
     
    

1.extends是json-default,表示返回json对象格式。

2.result中param的name为root,里面设置的值就是action中要返回的JSON对象

需要封装对象Tree

public class TreeNode {	private static final long serialVersionUID = 1L;	private String id;   // 节点id	private String text; // 显示的节点文本	private String state = "open"; // 节点状态,'open'或者'closed',默认是'open'	private boolean checked;       // 指明检查节点是否选中.	public TreeNode() {}	public TreeNode(String id, String text, String state, boolean checked) {		this.id = id;		this.text = text;		this.state = state;		this.checked = checked;	}	//...省略setXX() getXX()}

首先查询所有parentid为空值的数据,然后同时判断该节点下是否有子节点，如果有则状态是关闭状态

当继续展开树的时候 会将该ID值传入,然后查询该节点的子节点。

action方法实现

import java.sql.Connection;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.ArrayList;import java.util.List;import com.home.util.ConnectionManager;/** * 查询数据使用JDBC进行操作  * */public class TreeAction {	private List
    
      treeNodes = new ArrayList
     
      (); //返回的JSON数据	private String id; // 树组件使用的ID	public String treeLoad() {		Statement sta = null;		ResultSet rs = null;		try {			Connection conn = ConnectionManager.getConnection();			sta = conn.createStatement();			String sql = "";			if (id == null) {  //如果id为null则是根节点 				sql = "select * from easyui_tree where parentid = ''";			} else {           //查询下面的子节点 				sql = "select * from easyui_tree where parentid = " + id;			}			rs = sta.executeQuery(sql);			while (rs.next()) {				String id = rs.getString("id");				String name = rs.getString("name");				TreeNode node = new TreeNode();				node.setId(id);				node.setText(name);				node.setChecked(false);				//判断是否有子节点，如果有则closed否则open				if(isChildrenNode(id)){					node.setState("closed");				}else{					node.setState("open");				}								treeNodes.add(node);			}			// 关闭所有资源			ConnectionManager.closeAll(rs, sta, conn);		} catch (SQLException e) {			e.printStackTrace();		}		return "success";	}	/**	 * 判断是否有子节点	 * 	 * @return	 */	public boolean isChildrenNode(String id) {		Boolean flag = false;		Statement sta = null;		ResultSet rs = null;		try {			Connection conn = ConnectionManager.getConnection();			sta = conn.createStatement();			String sql = "select * from easyui_tree where parentid = " + id;			rs = sta.executeQuery(sql);			while (rs.next()) {				flag = true;			}			// 关闭所有资源			ConnectionManager.closeAll(rs, sta, conn);		} catch (SQLException e) {			e.printStackTrace();		}		return flag;	}	public List
      
        getTreeNodes() {		return treeNodes;	}	public void setTreeNodes(List
       
         treeNodes) {		this.treeNodes = treeNodes;	}	public String getId() {		return id;	}	public void setId(String id) {		this.id = id;	}}
       
      
     
    

import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;public class ConnectionManager {	public static final String DRIVER = "com.mysql.jdbc.Driver";	public static final String URL = "jdbc:mysql://localhost:3306/easyui";	public static final String USERNAME = "root";	public static final String PASSWORD = "root";	/**	 * 通过静态代码块 注册数据库驱动	 */	static {		try {			Class.forName(DRIVER);		} catch (ClassNotFoundException e) {			e.printStackTrace();		}	}	/**	 * 获得Connection	 * 	 * @return	 */	public static Connection getConnection() {		Connection conn = null;		try {			conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);		} catch (SQLException e) {			e.printStackTrace();		}		return conn;	}	/**	 * 关闭ResultSet	 * 	 * @param rs	 */	public static void closeResultSet(ResultSet rs) {		if (rs != null) {			try {				rs.close();			} catch (SQLException e) {				e.printStackTrace();			}		}	}	/**	 * 关闭Statement	 * 	 * @param st	 */	public static void closeStatement(Statement st) {		if (st != null) {			try {				st.close();			} catch (SQLException e) {				e.printStackTrace();			}		}	}	/**	 * 关闭Connection	 * 	 * @param conn	 */	public static void closeConnection(Connection conn) {		if (conn != null) {			try {				conn.close();			} catch (SQLException e) {				e.printStackTrace();			}		}	}	/**	 * 关闭全部	 * 	 * @param rs	 * @param sta	 * @param conn	 */	public static void closeAll(ResultSet rs, Statement sta, Connection conn) {		closeResultSet(rs);		closeStatement(sta);		closeConnection(conn);	}}

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