Question

我想在前端使用onload事件触发Servlet，然后通过Servlet中的SQL查询语句获取结果集，将结果集存储在JavaBean中，并在转发后将其显示在首页上

我使用了Tomcat版本9.0，MySql 8.0和最新版本的Eclipse

< html > <head > </head>
 <body>
  < head > 
  <script type="text/javascript ">
function f() {
    $.ajax({
        url: "DCommodityServlet ",
        //servlet文件的名称
        type: "post ",
        success: function(e) {
            alert("servlet调用成功！");
        }
    });

} < /script>
</head > <body onload = "f()" >

request.setCharacterEncoding("utf - 8 ");
String user = "root ";
String password = "123456 ";
HttpSession session = request.getSession(true);
Connection con = null;
DCommodity DCommodityBean = null;
DCommodityBean = new DCommodity();
session.setAttribute("DCommodityBean ", DCommodityBean);
String uri = "jdbc: mysql: //localhost:3306/test?useSSL=false&serverTimezone=UTC";
try {
    con = DriverManager.getConnection(uri, user, password);
    Statement sql = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
    ResultSet rs = sql.executeQuery("SELECT * FROM commodity ");
    ResultSetMetaData metaData = rs.getMetaData();
    int columnCount = metaData.getColumnCount();
    String[] columnName = new String[columnCount];
    for (int i = 0; i < columnName.length; i++) {
        columnName[i] = metaData.getColumnName(i + 1);
    }
    DCommodityBean.setColumnName(columnName);
    rs.last();
    int rowNumber = rs.getRow();
    String[][] tableRecord = DCommodityBean.getTableRecord();
    tableRecord = new String[rowNumber][columnCount];
    rs.beforeFirst();
    int i = 0;
    while (rs.next()) {
        for (int k = 0; k < columnCount; k++) tableRecord[i][k] = rs.getString(k + 1);
        i++;
    }
    DCommodityBean.setTableRecord(tableRecord);
    con.close();
    request.getRequestDispatcher("DCommodity.jsp").forward(request, response);
} catch(SQLException e) {
    System.out.println(e);
} < /script>
 </body > </html>/

期望：我希望在调用Servlet之后从数据库查询并存储在javabeans中以在界面中显示的结果集实际结果：我得到一个没有结果的JavaBean

为什么我不能使用Onload事件来调用Servlet

0 个答案: