论坛的新用户如果我的帖子格式不正确或遵循指南，请致歉。我会很快得到它。所以这是我的问题。看看下面的代码。我已经删除了几乎所有的外部位，以便将注意力集中在一个关键线上 -
LParts:=LJsonObj.Get('parts').JsonValue;
我在顶部（Const）有一些经过测试有效的JSON格式数据。当我尝试解析它时，它在运行时失败（编译时间很好）。我把所有这些都减少到了更小，更容易处理的东西。
当我在调试器中启动它时，它似乎都是有效的，但即使添加了Nil值的测试也不会对我对问题的理解产生太多影响。
我希望有人知道问题可能是什么。这是代码片段：
program ReadJSONConsoleApp;
{$APPTYPE CONSOLE}
{$R *.res}
uses
DBXJSON,
System.SysUtils;
Const
StrJson=
'{' +
' "response": {' +
' "distributor": {' +
' "id": 1538,' +
' "name": "Arrow Electronics",' +
' "authorized": true,' +
' "logoUrl": "this is normally a URL but I cut it out"' +
' },' +
' "parts": [' +
' {' +
' "manufacturer": "National Semiconductor",' +
' "part": "LM741WG/883",' +
' "description": "OP Amp Single GP ±22V 10-Pin CFPAK Tray",' +
' "price": [' +
' {' +
' "quantity": 0,' +
' "price": 65,' +
' "currency": "USD"' +
' }' +
' ],' +
' "stock": 88,' +
' "lastUpdated": "2013-11-04 18:27:16 UTC"' +
' },' +
' {' +
' "manufacturer": "National Semiconductor",' +
' "part": "LM741W/883",' +
' "description": "OP Amp Single GP ±22V 10-Pin CPAK Rail",' +
' "price": [' +
' {' +
' "quantity": 0,' +
' "price": 40.5,' +
' "currency": "USD"' +
' }' +
' ],' +
' "stock": 1464,' +
' "lastUpdated": "2013-11-04 18:27:16 UTC"' +
' },' +
' {' +
' "manufacturer": "Texas Instruments",' +
' "part": "LM741CH",' +
' "description": "OP Amp Single GP ±18V 8-Pin TO-99 Box",' +
' "price": [' +
' {' +
' "quantity": 0,' +
' "price": 5.22,' +
' "currency": "USD"' +
' }' +
' ],' +
' "stock": 95,' +
' "lastUpdated": "2013-11-04 18:27:16 UTC"' +
' }' +
' ]' +
' }' +
'}';
procedure ParseJson;
var
LJsonObj : TJSONObject;
LJPair : TJSONPair;
LParts : TJSONValue;
LPart : TJSONValue;
LItem : TJSONValue;
LIndex : Integer;
LSize : Integer;
begin
LJsonObj := TJSONObject.ParseJSONValue(TEncoding.ASCII.GetBytes(StrJson),0) as TJSONObject;
try
LParts:=LJsonObj.Get('parts').JsonValue;
{LSize:=TJSONArray(LParts).Size;
for LIndex:=0 to LSize-1 do
begin
LPart := TJSONArray(LParts).Get(LIndex);
LJPair := TJSONPair(LPart);
Writeln(Format('Part Name %s',[LJPair.JsonString.Value]));
for LItem in TJSONArray(LJPair.JsonValue) do
begin
if TJSONPair(LItem).JsonValue is TJSONFalse then
Writeln(Format(' %s : %s',[TJSONPair(LItem).JsonString.Value, 'false']))
else
if TJSONPair(LItem).JsonValue is TJSONTrue then
Writeln(Format(' %s : %s',[TJSONPair(LItem).JsonString.Value, 'true']))
else
Writeln(Format(' %s : %s',[TJSONPair(LItem).JsonString.Value, TJSONPair(LItem).JsonValue.Value]));
end;
end; }
finally
LJsonObj.Free;
end;
end;
begin
try
ParseJson;
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
Readln;
end.
再次感谢您，感谢您对我的耐心。
亲切的问候，
EEJoe
答案 0 :(得分：4)
用于解析JSON响应的代码与JSON字符串的结构无关。首先推荐的是JSON documentation，很容易理解。
试用带注释的示例代码
uses
DBXJSON,
System.SysUtils;
Const
StrJson=
'{' +
' "response": {' +
' "distributor": {' +
' "id": 1538,' +
' "name": "Arrow Electronics",' +
' "authorized": true,' +
' "logoUrl": "this is normally a URL but I cut it out"' +
' },' +
' "parts": [' +
' {' +
' "manufacturer": "National Semiconductor",' +
' "part": "LM741WG/883",' +
' "description": "OP Amp Single GP ±22V 10-Pin CFPAK Tray",' +
' "price": [' +
' {' +
' "quantity": 0,' +
' "price": 65,' +
' "currency": "USD"' +
' }' +
' ],' +
' "stock": 88,' +
' "lastUpdated": "2013-11-04 18:27:16 UTC"' +
' },' +
' {' +
' "manufacturer": "National Semiconductor",' +
' "part": "LM741W/883",' +
' "description": "OP Amp Single GP ±22V 10-Pin CPAK Rail",' +
' "price": [' +
' {' +
' "quantity": 0,' +
' "price": 40.5,' +
' "currency": "USD"' +
' }' +
' ],' +
' "stock": 1464,' +
' "lastUpdated": "2013-11-04 18:27:16 UTC"' +
' },' +
' {' +
' "manufacturer": "Texas Instruments",' +
' "part": "LM741CH",' +
' "description": "OP Amp Single GP ±18V 8-Pin TO-99 Box",' +
' "price": [' +
' {' +
' "quantity": 0,' +
' "price": 5.22,' +
' "currency": "USD"' +
' }' +
' ],' +
' "stock": 95,' +
' "lastUpdated": "2013-11-04 18:27:16 UTC"' +
' }' +
' ]' +
' }' +
'}';
procedure ParseJson;
var
LJsonObj : TJSONObject;
LRoot, LParts : TJSONValue;
LPart : TJSONValue;
LItem, LPrice : TJSONValue;
LIndex : Integer;
LSize : Integer;
begin
LJsonObj := TJSONObject.ParseJSONValue(TEncoding.ASCII.GetBytes(StrJson),0) as TJSONObject;
try
//get the root element
LRoot:=LJsonObj.Get('response').JsonValue;
// get the "parts" element
LParts:=TJSONObject(LRoot).Get('parts').JsonValue;
LSize:=TJSONArray(LParts).Size;
//iterate over the "parts"
for LIndex:=0 to LSize-1 do
begin
//extract the value of each pair
LPart := TJSONArray(LParts).Get(LIndex);
LItem:=TJSONObject(LPart).Get('manufacturer').JsonValue;
Writeln(Format('%s : %s',['manufacturer', LItem.Value]));
LItem:=TJSONObject(LPart).Get('part').JsonValue;
Writeln(Format('%s : %s',['part', LItem.Value]));
LItem:=TJSONObject(LPart).Get('description').JsonValue;
Writeln(Format('%s : %s',['description', LItem.Value]));
//the price is an array, so we need a little more of work
LItem:=TJSONObject(LPart).Get('price').JsonValue;
LPrice:=TJSONObject(TJSONArray(LItem).Get(0)).Get('quantity').JsonValue;
Writeln(Format(' %s : %s',['quantity', LPrice.Value]));
LPrice:=TJSONObject(TJSONArray(LItem).Get(0)).Get('price').JsonValue;
Writeln(Format(' %s : %s',['price', LPrice.Value]));
LPrice:=TJSONObject(TJSONArray(LItem).Get(0)).Get('currency').JsonValue;
Writeln(Format(' %s : %s',['currency', LPrice.Value]));
LItem:=TJSONObject(LPart).Get('stock').JsonValue;
Writeln(Format('%s : %s',['stock', LItem.Value]));
LItem:=TJSONObject(LPart).Get('lastUpdated').JsonValue;
Writeln(Format('%s : %s',['lastUpdated', LItem.Value]));
Writeln;
end;
finally
LJsonObj.Free;
end;
end;
begin
try
ParseJson;
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
Readln;
end.