触发查询后我有一个ResultSet.请告诉我如何将其转换为JSP中的
JSON输出.
在第二阶段,我们假设我们有一个JSON输出,就像在这个链接> http://inknpost.com/eshopping/json.jsp
解决方法
创建一个可重用的Javabean类,它表示一行,一个实体.
public class Category {
private Long id;
private String name;
private String department;
// Add/generate getters/setters/c'tors/equals/hashcode and other boilerplate.
}
创建一个可重用的DAO类,它以通常的JDBC方式将ResultSet映射到这些Javabeans的集合.
public class CategoryDAO {
private static final String sql_LIST = "SELECT id,name,department FROM category";
// ...
public List<Category> list() throws sqlException {
List<Category> categories = new ArrayList<Category>();
try (
Connection connection = database.getConnection();
PreparedStatement statement = connection.prepareStatement(sql_LIST);
ResultSet resultSet = statement.executeQuery();
) {
while (resultSet.next()) {
Category category = new Category();
category.setId(resultSet.getLong("id"));
category.setName(resultSet.getString("name"));
category.setDepartment(resultSet.getString("department"));
categories.add(category);
}
}
return categories;
}
// ...
}
创建一个servlet类,它使用JSON序列化器/反序列化器,它能够在Javabeans的arbirary集合和JSON字符串之间进行转换,例如Google Gson.
@WebServlet("/categories.json")
public class CategoriesJsonServlet extends HttpServlet {
@Override
public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException {
try {
List<Category> categories = categoryDAO.list();
String categoriesJson = new Gson().toJson(categories);
response.setContentType("application/json");
response.setCharacterEncoding("UTF-8");
response.getWriter().write(categoriesJson);
} catch (sqlException e) {
throw new ServletException("DB error",e);
}
}
}
通过http：// localhost：8080 / contextname / categories.json调用它.不,没有涉及JSP.您不应该将JSP用于HTML以外的输出格式.
最后,在jQuery中,只需访问它通常的$.getJSON()方式.
$('#somebutton').click(function() {
$.getJSON('categories.json',function(categoriesJson) {
var $table = $('<table>').appendTo($('#somediv'));
$.each(categoriesJson,function(index,category) {
$('<tr>').appendTo($table)
.append($('<td>').text(category.id))
.append($('<td>').text(category.name))
.append($('<td>').text(category.department));
});
});
});
