用JavaScript实现图片上传并预览-蒲公英云

一、前端界面是通过jqgrid展示的

jqgrid是典型的B／C架构（浏览器／服务器模式），服务器端只需提供数据管理，浏览器只需负责数据显示。

jqGrid是用ajax实现对请求和响应的处理，支持局部实时刷新。

二、jqgrid特性

1、通过配置url地址数据显示格式

2、支持行编辑，列搜索过滤

3、支持分页

4、添加表单支持文件上传

5、链式调用

三、代码实例

1、jqgrid页面展示

$(document).ready(function () {
    $("#gridTable").jqGrid({
        colNames:['标号','班次', '第一班', '第二班', '第三班', '第四班','操作'],
        colModel:[{
                name:'mark',
                index:'mark',
                width: 100,
            },{
                name:'division',
                index:'division',
                width: 100,
            },{
                name:'first_class',
                index:'first_class',
                width: 100,
            }, {
                name:'second_class',
                index:'second_class',
                width: 100,
            },{
                name:'third_class',
                index:'third_class',
                width: 100,
            }, {
                name: 'fouth_class',
                index: 'fouth_class',
                width: 100,
            }, {
                name: 'operate',
                index: 'operate',
                width: 200,
                search: false,
                formatter : function(cellvalue,options,rowObject){
                    var id = rowObject.mark
                    var str =   '<button class="btn-info" data-for="pictureModal">'+
                        '图片'+
                        '</button>';
                    return str;
                },
            }
        ],
        sortname : "mark",
        sortorder : "desc",
        viewrecords : true,
        width: 747,
        height: 355,
        rowNum: 10,
        datatype: 'text',
        pager: "#gridPager",
        onSelectRow:function(rowid){
            grid_selectRow = $("#gridTable").jqGrid("getRowData",rowid);
            $("#modal_picture").pictureLoading({});
        },
        ondblClickRow: function(rowid) {
            grid_selectRow = $("#gridTable").jqGrid("getRowData",rowid);
            $("#edit").trigger("click");
        },
    });
    jf_initJqgrid();
    jf_click();
    function jf_initJqgrid(){
        $.ajax({
            url:"DivisiondefineServlet",
            async:true,   //是否为异步请求
            cache:false,  //是否缓存结果
            type:"GET",
            dataType:"json",
            success : function(data){
                $("#gridTable").jqGrid("clearGridData");
                for(var i=0;i<=data.length;i++){
                    $("#gridTable").jqGrid('addRowData',i+1,data[i]);
                }
            }
        })
    }
    $('[id^=jqgh_gridTable_]').css("height","20px");
    function jf_click() {
        $("#add").click(function () {
            $("#modal-divisionAdd").divisionAdd({});
        })
        $("#edit").click(function () {
            $("#modal-divisionEdit").divisionEdit({});
        })
        $("#delete").click(function () {
            jf_delete();
            jf_initJqgrid();
        })
    }
    function jf_delete() {
        $.ajax({
            url:"DivisiondefineServlet?action=delete",
            async:true,   //是否为异步请求
            cache:false,  //是否缓存结果
            type:"POST",
            dataType:"text",
            data :{
                "mark1" : grid_selectRow.mark,
            },
        })
    }
});

2、模块页面

;(function($){
    $.fn.pictureLoading = function(options){
        var el = this;
        var opts = {
        }
        var param = $.extend(opts,options);
        var or = new Order(el, param);
    }
    var Order = function(el,param){
        this.el=el;
        this.param=param;
        this.orderContent();
        this.bindEvent();
        this.orderSetValue();
    }
    Order.prototype = {
        orderContent : function(){
            //创建模态窗体
            this.el.addClass("modal").attr("tabindex","-1").attr("data-backdrop","static");
            html=   '<div class="modal-dialog">'+
                        '<div class="modal-content" style="width: 450px">'+
                            '<div class="modal-header" style="border-bottom:0px;">'+
                                '<div class="row col-sm-12">'+
                                    '<div class="col-sm-8" align="left">'+
                                        '<span></span>'+
                                    '</div>'+
                                    '<div class="col-sm-4" align="right">'+
                                        '<button class="close" data-dismiss="modal" aria-hidden="true" value="HTML">'+
                                        '<span class="blue">×</span>'+
                                        '</button>'+
                                    '</div>'+
                                '</div>'+
                            '</div>'+
                            '<div class="modal-body" style="height:350px;top: -30px">'+
                                '<form  id="form"  action="PictureServlet" method="post">'+
                                    '<span>标号</span><input id="mark" name="mark" disabled/>'+
                                    '<span id="FPicName">'+
                                    '<input id="IronMan" type="file" size="45" name="IronMan" class="avatar input" οnchange="loadfile(); "style="display:none";/>'+
                                    '<img id="viewImg" class="viewImg" src="picture/html.jpg" style="height: 300px;width: 400px;" ="loadPic();" >'+
                                    '</span>'+
                                '</form>'+
                            '</div>'+
                            '<div class="modal-footer">'+
                                '<div align="right">'+
                                    '<div class="btn-group">'+
                                        '<button id="btnSubCancel" class="btn btn-default btn-sm" data-dismiss="modal">'+
                                        '<span>退出</span>'+
                                        '</button>'+
                                    '</div>'+
                                '</div>'+
                            '</div>'+
                        '</div>'+
                    '</div>';
            this.el.html("");
            this.el.append(html);
            this.el.modal("show");
        },
        orderSetValue : function(){
            $("#mark").val(grid_selectRow.mark);
            $.ajax({
                url:"PictureServlet",
                async:true,   //是否为异步请求
                cache:false,  //是否缓存结果
                type:"GET",
                dataType:"json",
                data :{
                    "mark" : $("#mark").val()
                },
                success : function(data){
                    $('#viewImg').attr('src', "../../../picture/" + data);
                },
                error:function () {
                    alert("error");
                }
            })
        },
        //自定义JS点击事件
        bindEvent : function(){
        },
    }
})(jQuery)

3、ajax实现异步请求

function loadfile(){
    var picName = $("#IronMan").val().replace("C:\fakepath\","");
    $.ajax({
        url:"PictureServlet",
        async:true,   //是否为异步请求
        cache:false,  //是否缓存结果
        type:"POST",
        dataType:"json",
        data :{
            "mark" : $("#mark").val(),
            "picName":picName,
        },
    })
    $('#viewImg').attr('src', "../../../picture/" + picName);
}

4、servlet存储并在本地存储图片文件

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws  IOException {
        System.out.println("servlet");
        response.setContentType("text/html");
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        int mark = Integer.parseInt(request.getParameter("mark"));
        String picName = request.getParameter("picName");
        service.insertPic(mark,picName);
        String directory = "E:/GDKJ/others/imooc_pic";
        File file = new File(directory,picName);
        if(file.exists()) {
            System.out.println(file.getAbsolutePath());
            System.out.println(file.getName());
            System.out.println(file.length());
        } else {
            file.getParentFile().mkdirs();
            try {
                file.createNewFile();
            } catch (IOException e) {
                System.out.println("创建新文件时出现了错误。。。");
                e.printStackTrace();
            }
        }
    }