http断点续传简单实现（java)

/* &5?G-mn  
**SiteFileFetch.java XAe\s`  
*/ MDJc[am  
package NetFox; (8.{+8o  
import java.io.*; j~bAbOX12  
import java.net.*; ((XE\V\}Z  
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/ s,tY74'5  
public class SiteFileFetch extends Thread { -."kq.m*  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ~.J,A\F  
long[] nStartPos; //开始位置 tJNIr5o  
long[] nEndPos; //结束位置 av-#)E  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 bNGCOj  
long nFileLength; //文件长度 [)^mBVht  
boolean bFirst = true; //是否第一次取文件 GF8 -_X  
boolean bStop = false; //停止标志 sYJL-2JX  
File tmpFile; //文件下载的临时信息 hq=,Z1J  
DataOutputStream output; //输出到文件的输出流 #ly@;!M  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） mzWP8Hlw  
public SiteFileFetch(SiteInfoBean bean) throws IOException \<~}o I  
{ N2BI_,hI1  
siteInfoBean = bean; Z|G/^DK!
  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Us,)]W.S  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); t2- ^-g6  
if(tmpFile.exists ()) FZF @  
{ Oe51PEqn  
bFirst = false; RT^v:paNT2  
read_nPos(); 9Hd;353Q  
} !;S"&mcPDJ  
else `1Zhq+s  
{ OR:[J5M)  
nStartPos = new long[bean.getNSplitter()]; y`yZR _  
nEndPos = new long[bean.getNSplitter()]; _T5)n=|  
} rEdY>\'  
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} S,''>`w  
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public void run() LH2PTW\b!6  
{ 5{K}?*3hJ  
//获得文件长度 *FK`&(B+}  
//分割文件 :]PM_V|  
//实例FileSplitterFetch KVkMU?6  
//启动FileSplitterFetch线程 Kc #|Z  
//等待子线程返回 +H_MV=A^  
try{ TW7:q83{l  
if(bFirst) nPN?kO=]  
{ 9XLFHV("  
nFileLength = getFileSize(); <@G8ni  
if(nFileLength == -1) #]E(N~  
{ \L # INP4~  
System.err.println("File Length is not known!"); t9^A(Vh"-  
} 8 TiG3  
else if(nFileLength == -2) "B{ECM;  
{ \,&9  
System.err.println("File is not access!"); x[Im%k  
} LOvHkk@+  
else }7s>B24J  
{ ; A,#;
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for(int i=0;i<nStartPos.length;i++) CSTI?A"P  
{ g5Z#xszj+  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); !TKkec8$  
} p`F9Amb  
for(int i=0;i<nEndPos.length-1;i++) *|% ^0#$c  
{ B=Ym x2A9]  
nEndPos = nStartPos[i+1]; . ]@=es  
} 2HD]?:Fk7  
nEndPos[nEndPos.length-1] = nFileLength; WG7k(Sp]  
} pZ(Fx&fy  
} +nL+N  
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 k5`OH8G  
//启动子线程 $HJTj29/  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; {Qv>q$Q  
for(int i=0;i<nStartPos.length;i++) e:w&(is  
{ F_;DN: {  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), C&~1M}I  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), =1p8i  
nStartPos,nEndPos,i); Rp9fO?ZjHt  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); !#2=\LUC  
fileSplitterFetch.start(); ?GA&f2]a  
} L<V3KS2y  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), +7V{ABfGl  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); zYY$
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// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ziE*'p  
nEndPos = " + nFileLength); L';MP^  
// fileSplitterFetch[nPos.length-1].start(); CZ
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//等待子线程结束 3+Qxg+<  
//int count = 0; U]|agz>  
//是否结束while循环 E.`U`L  
boolean breakWhile = false; n5-)/R[z  
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while(!bStop) Ih}1%Jq  
{ pd[ncL  
write_nPos(); +pm[f["C.  
Utility.sleep(500); I6!5Yj]O"  
breakWhile = true; mmXm\]r>4  
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for(int i=0;i<nStartPos.length;i++) H5CR'Rp  
{ $?G"GQ!.  
if(!fileSplitterFetch.bDownOver) g
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{ m([(:.X/IX  
breakWhile = false; oX@ya3!Pz  
break; )tHaB,  
} ]uj=:@  
} vbx6I>\Y  
if(breakWhile) J_;N:7'p  
break; 9^"b*&>P  
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C?
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//count++; 1"7Sy3  
//if(count>4) xkNyvqcw  
// siteStop(); Rlnbdb;!k  
} :A %^^F%  
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System.err.println("文件下载结束！"); bzDIhnw  
} 8P7"&VY
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catch(Exception e){e.printStackTrace ();} ml0.$z  
} uwf 5!Z:>  
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//获得文件长度 {>LIMG-f  
public long getFileSize() D4eTTf
Q  
{ .:p2Tbo  
int nFileLength = -1; /+*#pDx/zW  
try{ Z=B_Ty  
URL url = new URL(siteInfoBean.getSSiteURL()); FGO[ |]7IN  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); b`yZ|j'ikd  
httpConnection.setRequestProperty("User-Agent","NetFox"); SK1!thQy  
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int responseCode=httpConnection.getResponseCode(); ~R$~&x(b  
if(responseCode>=400) a?|vQ*W  
{ *<N3_tx"  
processErrorCode(responseCode); [ EFMu;q  
return -2; //-2 represent access is error iovfo2!hD  
} Uz cx6sw  
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String sHeader; E$9Y
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for(int i=1;;i++) Ol"3a|  
{ !USd9  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 8
}H1_y-g[  
//Utility.log(in.readLine()); ?D,=37  
sHeader=httpConnection.getHeaderFieldKey(i); J PyOG_h  
if(sHeader!=null) Om{l>24i.\  
{ k#[F`  
if(sHeader.equals("Content-Length")) (b?{xf'
G  
{ oH
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 43?^7_l-  
break; H&r,FmI@  
} y;mj^/SxK  
} #HS]NA|e@  
else AL$&|=C-$  
break; iz
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} *Av"JAX  
} &g2 Eptx#  
catch(IOException e){e.printStackTrace ();} q-nSLE+_;  
catch(Exception e){e.printStackTrace ();} x^Yl*iq  
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Utility.log(nFileLength); syU9O&<  
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 Rqwzh@}  
return nFileLength; ,q(&
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} =@TQ>Qw%b  
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//保存下载信息（文件指针位置） ^pM+A6 XY  
private void write_nPos() $+.l*]  
{ l3N I$Zu  
try{ $/6;9d^  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 2[0JO.K 4  
output.writeInt(nStartPos.length); G'YH6x,  
for(int i=0;i<nStartPos.length;i++) BBcV9CGU  
{ TO%dw^{_`  
// output.writeLong(nPos); ^(viM?*  
output.writeLong(fileSplitterFetch.nStartPos); M#|dIbns H  
output.writeLong(fileSplitterFetch.nEndPos); _gKe%J&  
} PtqJ*Z  
output.close(); @EE."T9  
} -hC,
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catch(IOException e){e.printStackTrace ();} r`c_e)STO  
catch(Exception e){e.printStackTrace ();} >0p$(>N]  
} b64 @s2]  
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//读取保存的下载信息（文件指针位置） }|%eCVB  
private void read_nPos() ?g!V!VS2  
{ iH^z:%dP  
try{ ''\;z<v  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 8kP3+  
int nCount = input.readInt(); &rkEK4  
nStartPos = new long[nCount]; N'xSG`,Mg  
nEndPos = new long[nCount]; (E]!Z vE  
for(int i=0;i<nStartPos.length;i++) A(]H{>PMy  
{ jqr1V_3(  
nStartPos = input.readLong(); ;S xFp  
nEndPos = input.readLong(); gm9mg*aM  
} 5k|9gICyd*  
input.close(); i-yy/y-N  
} t>8XTqqi  
catch(IOException e){e.printStackTrace ();} Scv#zuv_  
catch(Exception e){e.printStackTrace ();} iAa;6mH  
} "`6n6r42  
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private void processErrorCode(int nErrorCode) $%VuSrZ&  
{ Qp`gswvE  
System.err.println("Error Code : " + nErrorCode); =_YG#yS  
} 0ZQ'_g|%  
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bI|2@HV2  
//停止文件下载 dL|+d:v  
public void siteStop() 0a"igq9t  
{ !n^OM?.
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bStop = true; u4Em%:Xj  
for(int i=0;i<nStartPos.length;i++) {mB0rKVm  
fileSplitterFetch.splitterStop();
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} 2Pc%fuC  
} v
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//负责部分文件的抓取 /  g 2b  
**FileSplitterFetch.java .jMq  
*/ A<;SnXm  
package NetFox;  gk`zA  
+**!@uY  
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import java.io.*; 1 hg}(Hix  
import java.net.*; JmEj{K<3I  
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public class FileSplitterFetch extends Thread { (rg;IXAq%  
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;2Q~0a|  
String sURL; //File URL vX]Gf4,  
long nStartPos; //File Snippet Start Position sUE?v9  
long nEndPos; //File Snippet End Position &>H!}"Yk  
int nThreadID; //Thread's ID KN-avu_Ix  
boolean bDownOver = false; //Downing is over mS0udHod  
boolean bStop = false; //Stop identical }`+B=h-dW  
FileAccessI fileAccessI = null; //File Access interface ,]T2$?|  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException  ^eoLAL  
{ tnLAJ+-M  
this.sURL = sURL; F`9]=T0  
this.nStartPos = nStart; $/nY5[  
this.nEndPos = nEnd; |^@dFOz  
nThreadID = id; vB+ '  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 .CFa9"<  
} Ao/ jt<  
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public void run() M`S0u~#tI  
{ '}Ri`  
while(nStartPos < nEndPos && !bStop) eilYA_FL.  
{ I"KN"v^  
+>4;Zd!@d  
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try{ f|sFlUu&  
URL url = new URL(sURL); )aX,%yK  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 6S~sVUL9`  
httpConnection.setRequestProperty("User-Agent","NetFox"); >|;aIa@9  
String sProperty = "bytes="+nStartPos+"-"; EAeqLtFqs  
httpConnection.setRequestProperty("RANGE",sProperty); ?mlNL/:  
Utility.log(sProperty); h>Hb`G<  
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InputStream input = httpConnection.getInputStream(); RVeEkv[qp  
//logResponseHead(httpConnection); _/O25% l  
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byte[] b = new byte[1024]; Bp@v,)8*  
int nRead; a+Ac[>  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) : >>@rF ,  
{ im @h -A]0  
nStartPos += fileAccessI.write(b,0,nRead); rl0<Ls  
//if(nThreadID == 1) %AQIGBcgL  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); $1v&azM.  
} J(6oL   
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Utility.log("Thread " + nThreadID + " is over!"); DY^;EZ!hb  
bDownOver = true; 0tU.(  
//nPos = fileAccessI.write (b,0,nRead); QV\eMuNy  
} QVtQx>K`  
catch(Exception e){e.printStackTrace ();} a1@Y3MQ;i  
} %HJK;   
} %plo=RF  
7.`fJf?   
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//打印回应的头信息 1/"WD?a  
public void logResponseHead(HttpURLConnection con) rdJR 2  
{ h*v8#\b$J_  
for(int i=1;;i++) H*)NLp  
{
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String header=con.getHeaderFieldKey(i); N ,z6y5Lu  
if(header!=null) >vA2A1WhW  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); G.UI|r/Kz  
Utility.log(header+" : "+con.getHeaderField(header)); gg8Uo G  
else *M"}z  
break; Y0X-Zqk'  
} z[;z>8|c  
} >FkWH7  
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public void splitterStop() 0L/n?bf  
{ $ , u+4h  
bStop = true; X*\J_  
} #{\%rWnCm  
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} E@b(1@  
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/* lg&t8FHa;  
**FileAccess.java pfI"36]F  
*//文件访问(定位，写) m|G'K[8  
package NetFox; T~='5iy|  
import java.io.*; q7E~+p(>(  
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public class FileAccessI implements Serializable{ %ALwz[~]  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 O`<KwUx !  
RandomAccessFile oSavedFile; j{Q9{}<e  
long nPos; r%+V8o  
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public FileAccessI() throws IOException v%iflCK  
{ ;-qO'V:;  
this("",0); ~W-PD  
} Uw7h=UQh  
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'  
public FileAccessI(String sName,long nPos) throws IOException _BP&n  
{ <Pi|J-Y  
oSavedFile = new RandomAccessFile(sName,"rw"); _+E5T*dk  
this.nPos = nPos; ilqy/fL#  
oSavedFile.seek(nPos); V]db'qB\  
} VB*oGG  
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_  
public synchronized int write(byte[] b,int nStart,int nLen) D-._z:_  
{ +O?KNZ  
int n = -1; =7m)sxj]w  
try{ ~o~!+`@q  
oSavedFile.write(b,nStart,nLen); pWJFz-  
n = nLen; V: TM]  
} L bmawi^  
catch(IOException e) XcUwr  
{ VG ;kPzze  
e.printStackTrace (); "[ZB+-|[0  
} LHo3 Niy.  
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return n; B e0ND2oo  
} [UWdW  
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} lUMS;H(  
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1`qMj0Y_  
/* IvtJ0  
**SiteInfoBean.java
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*/ hJpxf,?'K  
package NetFox; GE%Z9#E  
P 'od`  
hFy;ffs.  
public class SiteInfoBean { DrY:9[LP  
]Hefm?9*^  
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private String sSiteURL; //Site's URL ?WqT[MnK  
private String sFilePath; //Saved File's Path /n{omx  
private String sFileName; //Saved File's Name A#J`;5!Sc  
private int nSplitter; //Count of Splited Downloading File lHPd"3HDK  
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public SiteInfoBean() dQA'($  
{//nSplitter的缺省值为5 9CWezI+  
//default value of nSplitter is 5 )9"_J9G  
this("","","",5); r\-uJ~8N  
} ,NyY>~+  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) tnN.:%mZ  
{ nz=GlO'[  
sSiteURL= sURL; wc}5m Hs  
sFilePath = sPath; E%,^Yvh/  
sFileName = sName; FE (ev 9@  
this.nSplitter = nSpiltter; i/`m`qdg  
#Oc] @  
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} keX,d#  
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public String getSSiteURL() bU2Z[sn.  
{ ][+#;avU  
return sSiteURL; 5A3xVN=  
} 26I_YL,S  
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i%#+\F.&  
public void setSSiteURL(String value) [ 0KlC1=  
{ xy/`ZS2WPq  
sSiteURL = value; {E9+WFz5  
} d"*uB
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public String getSFilePath() |@ s,XS  
{ F@'Jbd`   
return sFilePath; BW}U%B^.  
} qG?Qc (  
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public void setSFilePath(String value) z"-u95H  
{ "$+Jnc!!  
sFilePath = value; lm-dW'7&  
} P3x= 8_#  
' V^6XI  
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public String getSFileName() 4ew" %Cs*  
{ N~goI#4  
return sFileName; t^R][Ay&  
} bnq;)>&  
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cdl&9-}  
public void setSFileName(String value) pN:Kdi  
{ bpJ(XN}E  
sFileName = value; ;g5m0l5  
} -:Da&V  
t{^*6XOcJ  
Z'`gJ&6n  
public int getNSplitter() Xqg@ e:g  
{ [!HEQ8 2g  
return nSplitter; "GMBjT8  
} P;=n9hgHI  
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public void setNSplitter(int nCount) |:q=T ~x  
{ v7BA[jQr  
nSplitter = nCount; D[aCsaR  
} dx5#\"KX=,  
} A&.WH?p  
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o
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/* 0QXVW}`hz  
**Utility.java  Ch&a/S}  
*/ M -cTRd-i  
package NetFox; I5 o)_nc  
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public class Utility { ?26I,:;  
ieDk;  
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public Utility() #%
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{ @Owb?(6?  
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=x%dNf$e{W  
} :~b3^xhc^  
8;b(0^  
//线程睡眠 [YRz*5  
public static void sleep(int nSecond) ?*[N_'2W+  
{ \\r)Ue]  
try{ 8p^bD}lN7  
Thread.sleep(nSecond); |{BIHgMh  
} X[*<NN  
catch(Exception e) FOv=!'So  
{ *W4m3Lq  
e.printStackTrace (); 9_
# >aOqL  
} x[wq]q#*  
} fM]+SMZy  
@K\~O__  
//日志 M>wYD\oeg  
public static void log(String sMsg) D"Bl:W'?j  
{ /7aBDc-v  
System.err.println(sMsg); yh Yb'GK  
} s>B5l2Q4  
j`JMeCG=Ee  
)
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public static void log(int sMsg) iZ#!O*>  
{ ]{)a,c NG  
System.err.println(sMsg); aGrIQq/k)%  
} Ttu2skcv  
} p#ol*m5wE  
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hv`~?n)D66  
/* N|8P)  
**TestMethod.java <":;+Ng+  
*/ dbwe?ksh  
package NetFox; qW$<U3u}  
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 AsQ)q  
public class TestMethod { ~+Rc}K  
R+2+-j4  
fV &KM*W*@  
public TestMethod() *"+=K,#D  
{ ///xx/weblogic60b2_win.exe #zG&|<hc  
try{ 6.CbAi3Z  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); gQ
o]  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ;\a YlV-  
SiteFileFetch fileFetch = new SiteFileFetch(bean); %7"q"A r[  
fileFetch.start(); _BM" ]t*  
} nG,A@/N  
catch(Exception e){e.printStackTrace ();} >QjAoDVX?  
X}=n:Ql'YY  
^`*9QjY  
} Y'c>:;JEe  
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public static void main(String[] args) R}G4rO-J  
{ NO~*T?&  
new TestMethod(); Uddr~2%(  
} p31NIf`  
} >sfRI]OG  
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