wx.openDocument({

                  filePath:savedFilePath,

                  showMenu:true,

                  fileType: 'pdf',

                  success :function (res) {

                    wx.hideLoading()

                  },

                  fail:function ( error) {

                    wx.showToast({

                      title: '打开文件失败',   //这里打开失败

                      icon: 'none'

                    })

                  }

                })

文件打开失败