Question

我正在尝试制作在线Cantor。我需要从外部API确切地从该页面获取具有货币值的表：http://api.nbp.pl/api/exchangerates/tables/A?format=json 我想在货币课上得到答案。有人可以帮我完成这项任务吗？

@Service
public class CurrentFromNBPImpl implements CurrentFromNBP {

@Override
public Currency getValueOfCurrency(String currencyCode) throws WrongCurrencyCode {

    Currency currency = null;

    try {
        URL url = new URL("http://api.nbp.pl/api/exchangerates/tables/A?format=json");
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("GET");
        connection.setRequestProperty("Content-Type", "application/json");

        if (connection.getResponseCode() == 404)
            throw new WrongCurrencyCode(currencyCode);

        InputStreamReader inputStreamReader = new InputStreamReader(connection.getInputStream());
        BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
        String jsonOutput = bufferedReader.readLine();

        connection.disconnect();

        ObjectMapper objectMapper = new ObjectMapper();
        Currency list = objectMapper.readValue(jsonOutput, Currency.class);
        System.out.println(list);
    } catch (IOException e) {
        e.printStackTrace();
    }

    assert false;
    return currency;
}
}



@Data
public class Currency {

    @JsonProperty("table")
    private String table;
    @JsonProperty("no")
    private String no;
    @JsonProperty("effectiveDate")
    private String effectiveDate;
    @JsonProperty("rates")
    private List<Rate> rates = null;

}
@Data
public class Rate {

    @JsonProperty("currency")
    private String currency;
    @JsonProperty("code")
    private String code;
    @JsonProperty("mid")
    private Double mid;

    }

日志： com.fasterxml.jackson.databind.exc.MismatchedInputException：无法从START_ARRAY令牌中反序列化com.kolej.bartosz.challenge.domain.Currency的实例在[来源：（String）“ [{” table“：” A“，” no“：” 062 / A / NBP / 2019“，”有效日期“：” 2019-03-28“，”费率“：[{ “ currency”：“ bat（Tajlandia）”，“ code”：“ THB”，“ mid”：0.1202}，{“ currency”：“ dolaramerykański”，“ code”：“ USD”，“ mid”：3.8202} ，{“ currency”：“ dolar australijski”，“ code”：“ AUD”，“ mid”：2.7098}，{“ currency”：“ dolar Hongkongu”，“ code”：“ HKD”，“ mid”：0.4867} ，{“ currency”：“ dolar kanadyjski”，“ code”：“ CAD”，“ mid”：2.8461}，{“ currency”：“ dolar nowozelandzki”，“ code”：“ NZD”，“ mid”：2.6006} ，{“ currency”：“ dolar singapurski”，“ code”：“ SGD”，“ mid”：2.8179}，{“ currency”：“ eu” [被截断的1616个字符]；行：1，列：1]

Answer 1

您要反序列化的json对象是一个jsonArray。您需要反序列化为extern int obtain_order(); /* See parser.y for description */ int main(void) { char ***argvv; //int command_counter; int num_commands; //int args_counter; char *filev[3]; int bg; int ret; setenv("Acc","0",1); setbuf(stdout, NULL); /* Unbuffered */ setbuf(stdin, NULL); while (1) { fprintf(stderr, "%s", "msh> "); /* Prompt */ ret = obtain_order(&argvv, filev, &bg); if (ret == 0) break; /* EOF */ if (ret == -1) continue; /* Syntax error */ num_commands = ret - 1; /* Line */ if (num_commands == 0) continue; /* Empty line */ if(num_commands==1){ //Implementación propia para salir del mini-shell if(strcmp(argvv[0][0], "exit") == 0){ exit(0); } if(strcmp(argvv[0][0],"myTime")==0){ //HERE IS WHERE I HAVE TO IMPLEMENT THE INTERN COMMAND MYTIME }else{ //For all other commands ls, etc... (with pipes (max 3)and background) int pid; int estado; pid = fork(); switch(pid) { case -1: /* error */ fprintf(stderr, "%s","Error en el fork del mandato simple\n"); return (-1); case 0: /* hijo */ if (filev[0] != NULL) { close(STDIN_FILENO); open(filev[0],O_RDONLY); } if (filev[1] != NULL) { close(STDOUT_FILENO); open(filev[1],O_CREAT|O_WRONLY,0666); } if (filev[2] != NULL) { close(STDERR_FILENO); open(filev[2],O_CREAT|O_WRONLY,0666); } execvp(argvv[0][0], argvv[0]); fprintf(stderr, "%s","Error en el execvp del mandato simple\n"); return(-1); default: /* padre */ if(!bg){ while (wait(&estado) != pid); }else printf("%d\n",pid); } //fin switch (1 mandato) } //fin if (si es comando interno o no) }else if(num_commands==2){ int pid; int estado; int fd[2]; pipe(fd); pid = fork(); switch(pid) { case -1: /* error */ fprintf(stderr, "%s","Error en el fork del primer mandato\n"); return (-1); case 0: /* hijo1 */ close(STDOUT_FILENO); dup(fd[1]); close(fd[0]); close(fd[1]); if (filev[0] != NULL) { close(STDIN_FILENO); open(filev[0],O_RDONLY); } if (filev[2] != NULL) { close(STDERR_FILENO); open(filev[2],O_CREAT|O_WRONLY,0666); } execvp(argvv[0][0], argvv[0]); fprintf(stderr, "%s","Error en el execvp del primer mandato\n"); return(-1); default: /* padre */ pid = fork(); switch(pid) { case -1: /* error */ fprintf(stderr, "%s","Error en el fork del segundo mandato\n"); return (-1); case 0: /* hijo 2*/ close(STDIN_FILENO); dup(fd[0]); close(fd[0]); close(fd[1]); if (filev[1] != NULL) { close(STDOUT_FILENO); open(filev[1],O_CREAT|O_WRONLY,0666); } if (filev[2] != NULL) { close(STDERR_FILENO); open(filev[2],O_CREAT|O_WRONLY,0666); } execvp(argvv[1][0], argvv[1]); fprintf(stderr, "%s","Error en el execvp del segundo mandato\n"); return(-1); default: /* padre */ close(fd[0]); close(fd[1]); if(!bg){ while (wait(&estado) != pid); }else printf("%d\n",pid); } //fin switch2 (2 mandatos) } //fin switch1 (2 mandatso) }else if(num_commands==3){ int pid; int estado; int fd[2], fd2[2]; pipe(fd); pid = fork(); switch(pid) { case -1: /* error */ fprintf(stderr, "%s","Error en el fork del primer mandato\n"); return (-1); case 0: /* hijo1 */ close(STDOUT_FILENO); dup(fd[1]); close(fd[0]); close(fd[1]); if (filev[0] != NULL) { close(STDIN_FILENO); open(filev[0],O_RDONLY); } if (filev[2] != NULL) { close(STDERR_FILENO); open(filev[2],O_CREAT|O_WRONLY,0666); } execvp(argvv[0][0], argvv[0]); fprintf(stderr, "%s","Error en el execvp del primer mandato\n"); return(-1); default: /* padre */ pipe(fd2); pid = fork(); switch(pid) { case -1: /* error */ fprintf(stderr, "%s","Error en el fork del segundo mandato\n"); return (-1); case 0: /* hijo 2*/ close(STDIN_FILENO); dup(fd[0]); close(STDOUT_FILENO); dup(fd2[1]); close(fd[0]); close(fd[1]); close(fd2[0]); close(fd2[1]); if (filev[2] != NULL) { close(STDERR_FILENO); open(filev[2],O_CREAT|O_WRONLY,0666); } execvp(argvv[1][0], argvv[1]); fprintf(stderr, "%s","Error en el execvp del segundo mandato\n"); return(-1); default: /* padre */ close(fd[0]); close(fd[1]); pid = fork(); switch(pid) { case -1: /* error */ fprintf(stderr, "%s","Error en el fork del tercer mandato\n"); return (-1); case 0: /* hijo 3*/ close(STDIN_FILENO); dup(fd2[0]); close(fd2[0]); close(fd2[1]); if (filev[1] != NULL) { close(STDOUT_FILENO); open(filev[1],O_CREAT|O_WRONLY,0666); } if (filev[2] != NULL) { close(STDERR_FILENO); open(filev[2],O_CREAT|O_WRONLY,0666); } execvp(argvv[2][0], argvv[2]); fprintf(stderr, "%s","Error en el execvp del tercer mandato\n"); return(-1); default: /* padre */ close(fd2[0]); close(fd2[1]); if(!bg){ while (wait(&estado) != pid); }else printf("%d\n",pid); } //fin switch 3 (3 mandatos) } //fin switch2 (3 mandatos) } //fin switch1 (tres mandatos) } //fin if (número de mandatos) } //fin while return 0; } //fin main列表，而不是Currency。

Answer 2

您可以尝试

ArrayList<Currency> list = new ArrayList<>();
list = objectMapper.readValue(data, new TypeReference<ArrayList<Currency>>() {});

来自外部API的“无法反序列化的实例”

2 个答案: