首先jsp页面有一ul用于展现Tree

<ul id="mytree"></ul>  

加载Tree

<script type="text/javascript">
	$(‘#mytree‘).tree({   
	    url:‘treeLoad.action‘
	}); 
</script>

<struts>
	<package name="tree_json" extends="json-default">
		<action name="treeLoad" method="treeLoad" class="com.home.web.TreeAction">
			<result type="json">
				<param name="root">treeNodes</param>
			</result>
		</action>
	</package>
</struts>

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<TreeNode> treeNodes = new ArrayList<TreeNode>(); //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<TreeNode> getTreeNodes() {
		return treeNodes;
	}

	public void setTreeNodes(List<TreeNode> 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);
	}

}

项目源码下载：http://download.csdn.net/detail/itmyhome/7852021


转载请注明出处：http://blog.csdn.net/itmyhome1990/article/details/38818449

EasyUI实现异步加载tree(整合Struts2)